Revert of Update mojo sdk to rev c02a28868825edfa57ab77947b8cb15e741c5598 (patchset #1 id:1 of https://codereview.chromium.org/1310103002/ )

Reason for revert:
Looks like this breaks mojo_system_unittests on Android...

http://build.chromium.org/p/chromium.linux/buildstatus?builder=Android%20GN&number=29595

Original issue's description:
> Update mojo sdk to rev c02a28868825edfa57ab77947b8cb15e741c5598
>
> Re-land. Previously conflicted with another CL that landed
> just before the roll.
>
> BUG=None
> TBR=jam@chromium.org,ben@chromium.org
> TBR=mfoltz@chromium.org
> TBR=mek@chromium.org
> TBR=xhwang@chromium.org
> TBR=shess@chromium.org
>
> Committed: https://crrev.com/0bfe154baad9ddfb1f0c6ecc7cace36e8f430e75
> Cr-Commit-Position: refs/heads/master@{#344994}

TBR=ben@chromium.org,jam@chromium.org,mek@chromium.org,mfoltz@chromium.org,shess@chromium.org,xhwang@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=None

Review URL: https://codereview.chromium.org/1309103002

Cr-Commit-Position: refs/heads/master@{#344996}

138 files changed, 981 insertions, 2418 deletions

diff --git a/build/module_args/dart.gni b/build/module_args/dart.gni
deleted file mode 100644
index be5e83b..0000000
--- a/build/module_args/dart.gni
+++ /dev/null
@@ -1,6 +0,0 @@
-# Copyright 2015 The Chromium Authors. All rights reserved.
-# Use of this source code is governed by a BSD-style license that can be
-# found in the LICENSE file.
-
-# Mojo needs this file to exist. We don't currently need it to define anything.
-
diff --git a/chrome/browser/media/router/media_router_mojo_impl.h b/chrome/browser/media/router/media_router_mojo_impl.h
index 5c28a5a..c9053af 100644
--- a/chrome/browser/media/router/media_router_mojo_impl.h
+++ b/chrome/browser/media/router/media_router_mojo_impl.h
@@ -23,7 +23,6 @@
 #include "chrome/browser/media/router/issue_manager.h"
 #include "chrome/browser/media/router/media_router.h"
 #include "chrome/browser/media/router/media_router.mojom.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 namespace content {
 class BrowserContext;
diff --git a/chrome/browser/media/router/media_router_mojo_test.h b/chrome/browser/media/router/media_router_mojo_test.h
index 69db798..0a2e933 100644
--- a/chrome/browser/media/router/media_router_mojo_test.h
+++ b/chrome/browser/media/router/media_router_mojo_test.h
@@ -15,7 +15,6 @@
 #include "mojo/message_pump/message_pump_mojo.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 namespace media_router {
 
diff --git a/components/devtools_service/devtools_http_server.h b/components/devtools_service/devtools_http_server.h
index 6906db6..a4f4eed 100644
--- a/components/devtools_service/devtools_http_server.h
+++ b/components/devtools_service/devtools_http_server.h
@@ -12,7 +12,6 @@
 #include "mojo/services/network/public/interfaces/http_connection.mojom.h"
 #include "mojo/services/network/public/interfaces/http_message.mojom.h"
 #include "mojo/services/network/public/interfaces/http_server.mojom.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 namespace devtools_service {
 
diff --git a/components/filesystem/files_test_base.h b/components/filesystem/files_test_base.h
index 43ffccf..5388a9e 100644
--- a/components/filesystem/files_test_base.h
+++ b/components/filesystem/files_test_base.h
@@ -8,7 +8,6 @@
 #include "base/macros.h"
 #include "components/filesystem/public/interfaces/file_system.mojom.h"
 #include "mojo/application/public/cpp/application_test_base.h"
-#include "mojo/public/cpp/bindings/binding.h"
 
 namespace filesystem {
 
diff --git a/components/html_viewer/document_resource_waiter.h b/components/html_viewer/document_resource_waiter.h
index a2312e4..c0a2f62e 100644
--- a/components/html_viewer/document_resource_waiter.h
+++ b/components/html_viewer/document_resource_waiter.h
@@ -8,7 +8,6 @@
 #include "base/basictypes.h"
 #include "mandoline/tab/public/interfaces/frame_tree.mojom.h"
 #include "mojo/services/network/public/interfaces/url_loader.mojom.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 namespace mojo {
 class View;
diff --git a/components/html_viewer/html_frame.cc b/components/html_viewer/html_frame.cc
index 7699a33..5cb3223 100644
--- a/components/html_viewer/html_frame.cc
+++ b/components/html_viewer/html_frame.cc
@@ -73,6 +73,7 @@ using mojo::Rect;
 using mojo::ServiceProviderPtr;
 using mojo::URLResponsePtr;
 using mojo::View;
+using mojo::WeakBindToRequest;
 
 namespace html_viewer {
 namespace {
diff --git a/components/html_viewer/html_frame.h b/components/html_viewer/html_frame.h
index 8a82e15..7b47bdc 100644
--- a/components/html_viewer/html_frame.h
+++ b/components/html_viewer/html_frame.h
@@ -20,7 +20,6 @@
 #include "third_party/WebKit/public/web/WebSandboxFlags.h"
 #include "third_party/WebKit/public/web/WebTextInputInfo.h"
 #include "third_party/WebKit/public/web/WebViewClient.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 namespace blink {
 class WebFrame;
diff --git a/components/html_viewer/web_socket_handle_impl.cc b/components/html_viewer/web_socket_handle_impl.cc
index ef08b04..fa103d4 100644
--- a/components/html_viewer/web_socket_handle_impl.cc
+++ b/components/html_viewer/web_socket_handle_impl.cc
@@ -17,7 +17,6 @@
 #include "third_party/WebKit/public/platform/WebString.h"
 #include "third_party/WebKit/public/platform/WebURL.h"
 #include "third_party/WebKit/public/platform/WebVector.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 using blink::WebSecurityOrigin;
 using blink::WebSocketHandle;
diff --git a/content/browser/presentation/presentation_service_impl.cc b/content/browser/presentation/presentation_service_impl.cc
index 80e2aea..97b5ddd 100644
--- a/content/browser/presentation/presentation_service_impl.cc
+++ b/content/browser/presentation/presentation_service_impl.cc
@@ -169,10 +169,12 @@ void PresentationServiceImpl::Bind(
     mojo::InterfaceRequest<presentation::PresentationService> request) {
   binding_.reset(new mojo::Binding<presentation::PresentationService>(
       this, request.Pass()));
-  binding_->set_connection_error_handler([this]() {
-    DVLOG(1) << "Connection error";
-    delete this;
-  });
+  binding_->set_error_handler(this);
+}
+
+void PresentationServiceImpl::OnConnectionError() {
+  DVLOG(1) << "OnConnectionError";
+  delete this;
 }
 
 void PresentationServiceImpl::SetClient(
diff --git a/content/browser/presentation/presentation_service_impl.h b/content/browser/presentation/presentation_service_impl.h
index 0a3fe6f..2e991fa 100644
--- a/content/browser/presentation/presentation_service_impl.h
+++ b/content/browser/presentation/presentation_service_impl.h
@@ -26,7 +26,6 @@
 #include "content/public/browser/presentation_service_delegate.h"
 #include "content/public/browser/web_contents_observer.h"
 #include "content/public/common/frame_navigate_params.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 namespace content {
 
@@ -49,6 +48,7 @@ using NewSessionMojoCallback = mojo::Callback<
 // from the renderer when the first presentation API request is handled.
 class CONTENT_EXPORT PresentationServiceImpl
     : public NON_EXPORTED_BASE(presentation::PresentationService),
+      public mojo::ErrorHandler,
       public WebContentsObserver,
       public PresentationServiceDelegate::Observer {
  public:
@@ -198,6 +198,10 @@ class CONTENT_EXPORT PresentationServiceImpl
   // Creates a binding between this object and |request|.
   void Bind(mojo::InterfaceRequest<presentation::PresentationService> request);
 
+  // mojo::ErrorHandler override.
+  // Note that this is called when the RenderFrameHost is deleted.
+  void OnConnectionError() override;
+
   // WebContentsObserver override.
   void DidNavigateAnyFrame(
       content::RenderFrameHost* render_frame_host,
diff --git a/content/child/navigator_connect/service_port_provider.h b/content/child/navigator_connect/service_port_provider.h
index e99c9be..7764be0 100644
--- a/content/child/navigator_connect/service_port_provider.h
+++ b/content/child/navigator_connect/service_port_provider.h
@@ -11,7 +11,6 @@
 #include "content/child/worker_task_runner.h"
 #include "content/common/service_port_service.mojom.h"
 #include "third_party/WebKit/public/platform/modules/navigator_services/WebServicePortProvider.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 class GURL;
 
diff --git a/content/renderer/presentation/presentation_dispatcher.h b/content/renderer/presentation/presentation_dispatcher.h
index 71bbd0e..e332a46 100644
--- a/content/renderer/presentation/presentation_dispatcher.h
+++ b/content/renderer/presentation/presentation_dispatcher.h
@@ -5,8 +5,6 @@
 #ifndef CONTENT_RENDERER_PRESENTATION_PRESENTATION_DISPATCHER_H_
 #define CONTENT_RENDERER_PRESENTATION_PRESENTATION_DISPATCHER_H_
 
-#include <queue>
-
 #include "base/compiler_specific.h"
 #include "base/containers/scoped_ptr_map.h"
 #include "base/id_map.h"
@@ -16,7 +14,6 @@
 #include "content/common/presentation/presentation_service.mojom.h"
 #include "content/public/renderer/render_frame_observer.h"
 #include "third_party/WebKit/public/platform/modules/presentation/WebPresentationClient.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 namespace blink {
 class WebPresentationAvailabilityObserver;
diff --git a/content/renderer/usb/web_usb_client_impl.cc b/content/renderer/usb/web_usb_client_impl.cc
index ac4f681..84062d9 100644
--- a/content/renderer/usb/web_usb_client_impl.cc
+++ b/content/renderer/usb/web_usb_client_impl.cc
@@ -22,6 +22,7 @@
 #include "third_party/WebKit/public/platform/modules/webusb/WebUSBDeviceRequestOptions.h"
 #include "third_party/WebKit/public/platform/modules/webusb/WebUSBError.h"
 #include "third_party/mojo/src/mojo/public/cpp/bindings/array.h"
+#include "third_party/mojo/src/mojo/public/cpp/bindings/error_handler.h"
 #include "third_party/mojo/src/mojo/public/cpp/bindings/interface_request.h"
 
 namespace content {
diff --git a/content/renderer/usb/web_usb_device_impl.cc b/content/renderer/usb/web_usb_device_impl.cc
index d9b1dd8..e59d5bf 100644
--- a/content/renderer/usb/web_usb_device_impl.cc
+++ b/content/renderer/usb/web_usb_device_impl.cc
@@ -106,4 +106,8 @@ void WebUSBDeviceImpl::reset(blink::WebUSBDeviceResetCallbacks* callbacks) {
   RejectAsNotImplemented(callbacks);
 }
 
+void WebUSBDeviceImpl::OnConnectionError() {
+  device_.reset();
+}
+
 }  // namespace content
diff --git a/content/renderer/usb/web_usb_device_impl.h b/content/renderer/usb/web_usb_device_impl.h
index 3f6eab5..7f01d8d 100644
--- a/content/renderer/usb/web_usb_device_impl.h
+++ b/content/renderer/usb/web_usb_device_impl.h
@@ -14,6 +14,7 @@
 #include "third_party/WebKit/public/platform/modules/webusb/WebUSBDevice.h"
 #include "third_party/WebKit/public/platform/modules/webusb/WebUSBDeviceInfo.h"
 #include "third_party/WebKit/public/platform/modules/webusb/WebUSBError.h"
+#include "third_party/mojo/src/mojo/public/cpp/bindings/error_handler.h"
 
 namespace mojo {
 class Shell;
@@ -21,7 +22,7 @@ class Shell;
 
 namespace content {
 
-class WebUSBDeviceImpl : public blink::WebUSBDevice {
+class WebUSBDeviceImpl : public blink::WebUSBDevice, public mojo::ErrorHandler {
  public:
   WebUSBDeviceImpl(device::usb::DeviceManagerPtr device_manager,
                    const blink::WebUSBDeviceInfo& device_info);
@@ -61,6 +62,9 @@ class WebUSBDeviceImpl : public blink::WebUSBDevice {
                 blink::WebUSBDeviceBulkTransferCallbacks* callbacks) override;
   void reset(blink::WebUSBDeviceResetCallbacks* callbacks) override;
 
+  // mojo::ErrorHandler implementation:
+  void OnConnectionError() override;
+
   device::usb::DeviceManagerPtr device_manager_;
 
   blink::WebUSBDeviceInfo device_info_;
diff --git a/device/serial/data_receiver.h b/device/serial/data_receiver.h
index 0eba0a2..774d395 100644
--- a/device/serial/data_receiver.h
+++ b/device/serial/data_receiver.h
@@ -13,7 +13,6 @@
 #include "base/memory/weak_ptr.h"
 #include "device/serial/buffer.h"
 #include "device/serial/data_stream.mojom.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 #include "third_party/mojo/src/mojo/public/cpp/system/data_pipe.h"
 
 namespace device {
diff --git a/device/serial/data_sink_receiver.h b/device/serial/data_sink_receiver.h
index 733b0a1..8bb306e 100644
--- a/device/serial/data_sink_receiver.h
+++ b/device/serial/data_sink_receiver.h
@@ -13,7 +13,6 @@
 #include "base/memory/weak_ptr.h"
 #include "device/serial/buffer.h"
 #include "device/serial/data_stream.mojom.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 #include "third_party/mojo/src/mojo/public/cpp/system/data_pipe.h"
 
 namespace device {
diff --git a/device/serial/data_source_sender.h b/device/serial/data_source_sender.h
index 160dec9..2de7ce6 100644
--- a/device/serial/data_source_sender.h
+++ b/device/serial/data_source_sender.h
@@ -12,7 +12,6 @@
 #include "base/memory/weak_ptr.h"
 #include "device/serial/buffer.h"
 #include "device/serial/data_stream.mojom.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 #include "third_party/mojo/src/mojo/public/cpp/system/data_pipe.h"
 
 namespace device {
diff --git a/extensions/browser/mojo/stash_backend_unittest.cc b/extensions/browser/mojo/stash_backend_unittest.cc
index be76bac..ae14208 100644
--- a/extensions/browser/mojo/stash_backend_unittest.cc
+++ b/extensions/browser/mojo/stash_backend_unittest.cc
@@ -33,7 +33,7 @@ mojo::ScopedHandle CreateReadableHandle() {
 
 }  // namespace
 
-class StashServiceTest : public testing::Test {
+class StashServiceTest : public testing::Test, public mojo::ErrorHandler {
  public:
   enum Event {
     EVENT_NONE,
@@ -49,11 +49,11 @@ class StashServiceTest : public testing::Test {
     stash_backend_.reset(new StashBackend(base::Bind(
         &StashServiceTest::OnHandleReadyToRead, base::Unretained(this))));
     stash_backend_->BindToRequest(mojo::GetProxy(&stash_service_));
-    stash_service_.set_connection_error_handler(base::Bind(&OnConnectionError));
+    stash_service_.set_error_handler(this);
     handles_ready_ = 0;
   }
 
-  static void OnConnectionError() { FAIL() << "Unexpected connection error"; }
+  void OnConnectionError() override { FAIL() << "Unexpected connection error"; }
 
   mojo::Array<StashedObjectPtr> RetrieveStash() {
     mojo::Array<StashedObjectPtr> stash;
@@ -271,7 +271,7 @@ TEST_F(StashServiceTest, NotifyOncePerStashOnReadableHandles) {
 // exists.
 TEST_F(StashServiceTest, ServiceWithDeletedBackend) {
   stash_backend_.reset();
-  stash_service_.set_connection_error_handler(base::Bind(&OnConnectionError));
+  stash_service_.set_error_handler(this);
 
   mojo::Array<StashedObjectPtr> stashed_objects;
   StashedObjectPtr stashed_object(StashedObject::New());
diff --git a/ipc/mojo/ipc_channel_mojo.cc b/ipc/mojo/ipc_channel_mojo.cc
index ff20719..08c3458 100644
--- a/ipc/mojo/ipc_channel_mojo.cc
+++ b/ipc/mojo/ipc_channel_mojo.cc
@@ -16,7 +16,6 @@
 #include "ipc/mojo/ipc_mojo_bootstrap.h"
 #include "ipc/mojo/ipc_mojo_handle_attachment.h"
 #include "third_party/mojo/src/mojo/edk/embedder/embedder.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 #if defined(OS_POSIX) && !defined(OS_NACL)
 #include "ipc/ipc_platform_file_attachment_posix.h"
diff --git a/mandoline/ui/aura/surface_binding.cc b/mandoline/ui/aura/surface_binding.cc
index 5c20cca..0307112 100644
--- a/mandoline/ui/aura/surface_binding.cc
+++ b/mandoline/ui/aura/surface_binding.cc
@@ -24,7 +24,6 @@
 #include "mojo/cc/context_provider_mojo.h"
 #include "mojo/converters/geometry/geometry_type_converters.h"
 #include "mojo/converters/surfaces/surfaces_type_converters.h"
-#include "mojo/public/cpp/bindings/binding.h"
 
 namespace mandoline {
 namespace {
diff --git a/media/mojo/services/mojo_cdm.h b/media/mojo/services/mojo_cdm.h
index 96b4532..ea4e8a4 100644
--- a/media/mojo/services/mojo_cdm.h
+++ b/media/mojo/services/mojo_cdm.h
@@ -14,7 +14,6 @@
 #include "media/base/media_keys.h"
 #include "media/mojo/interfaces/content_decryption_module.mojom.h"
 #include "media/mojo/services/mojo_type_trait.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 namespace mojo {
 class ServiceProvider;
diff --git a/media/mojo/services/mojo_renderer_impl.h b/media/mojo/services/mojo_renderer_impl.h
index e574b15..f25fb4f 100644
--- a/media/mojo/services/mojo_renderer_impl.h
+++ b/media/mojo/services/mojo_renderer_impl.h
@@ -9,7 +9,6 @@
 #include "base/memory/weak_ptr.h"
 #include "media/base/renderer.h"
 #include "media/mojo/interfaces/renderer.mojom.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 namespace base {
 class SingleThreadTaskRunner;
diff --git a/mojo/application/public/cpp/application_impl.h b/mojo/application/public/cpp/application_impl.h
index 01088f8..9b587b2 100644
--- a/mojo/application/public/cpp/application_impl.h
+++ b/mojo/application/public/cpp/application_impl.h
@@ -15,7 +15,6 @@
 #include "mojo/application/public/cpp/lib/service_registry.h"
 #include "mojo/application/public/interfaces/application.mojom.h"
 #include "mojo/application/public/interfaces/shell.mojom.h"
-#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/bindings/callback.h"
 #include "mojo/public/cpp/system/core.h"
 
diff --git a/mojo/application/public/cpp/lib/service_registry.h b/mojo/application/public/cpp/lib/service_registry.h
index 8cb1d1b..7e4d604 100644
--- a/mojo/application/public/cpp/lib/service_registry.h
+++ b/mojo/application/public/cpp/lib/service_registry.h
@@ -11,7 +11,6 @@
 #include "mojo/application/public/cpp/application_connection.h"
 #include "mojo/application/public/cpp/lib/service_connector_registry.h"
 #include "mojo/application/public/interfaces/service_provider.mojom.h"
-#include "mojo/public/cpp/bindings/binding.h"
 
 namespace mojo {
 namespace internal {
diff --git a/mojo/gles2/command_buffer_client_impl.h b/mojo/gles2/command_buffer_client_impl.h
index 1ec0f1f..a01c12c 100644
--- a/mojo/gles2/command_buffer_client_impl.h
+++ b/mojo/gles2/command_buffer_client_impl.h
@@ -13,7 +13,6 @@
 #include "gpu/command_buffer/client/gpu_control.h"
 #include "gpu/command_buffer/common/command_buffer.h"
 #include "gpu/command_buffer/common/command_buffer_shared.h"
-#include "third_party/mojo/src/mojo/public/cpp/bindings/binding.h"
 
 namespace base {
 class RunLoop;
diff --git a/mojo/runner/child_process.cc b/mojo/runner/child_process.cc
index 8c62fdb..85ce4b3 100644
--- a/mojo/runner/child_process.cc
+++ b/mojo/runner/child_process.cc
@@ -26,7 +26,6 @@
 #include "mojo/edk/embedder/scoped_platform_handle.h"
 #include "mojo/edk/embedder/simple_platform_support.h"
 #include "mojo/message_pump/message_pump_mojo.h"
-#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/system/core.h"
 #include "mojo/runner/child_process.mojom.h"
 #include "mojo/runner/native_application_support.h"
diff --git a/mojo/tools/rev_sdk.py b/mojo/tools/rev_sdk.py
index fa222d8..d3d14c7 100755
--- a/mojo/tools/rev_sdk.py
+++ b/mojo/tools/rev_sdk.py
@@ -33,7 +33,6 @@ sdk_dirs_to_not_clone = [
 preserved_chromium_files = [
   'mojo/edk/DEPS',
   'mojo/public/DEPS',
-  'mojo/public/c/gpu/DEPS',
   'mojo/public/platform/nacl/DEPS',
   'nacl_bindings/DEPS',
 ]
diff --git a/sql/mojo/sql_test_base.h b/sql/mojo/sql_test_base.h
index d39198d..7a7ccca 100644
--- a/sql/mojo/sql_test_base.h
+++ b/sql/mojo/sql_test_base.h
@@ -9,7 +9,6 @@
 #include "base/memory/scoped_ptr.h"
 #include "components/filesystem/public/interfaces/file_system.mojom.h"
 #include "mojo/application/public/cpp/application_test_base.h"
-#include "mojo/public/cpp/bindings/binding.h"
 #include "sql/connection.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
diff --git a/third_party/mojo/mojo_edk.gyp b/third_party/mojo/mojo_edk.gyp
index 0b5b475..8f60ae6 100644
--- a/third_party/mojo/mojo_edk.gyp
+++ b/third_party/mojo/mojo_edk.gyp
@@ -24,6 +24,7 @@
       'dependencies': [
         '../../base/base.gyp:base',
         '../../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations',
+        '../../crypto/crypto.gyp:crypto',
       ],
       'includes': [
         'mojo_edk_system_impl.gypi',
@@ -140,6 +141,7 @@
           'dependencies': [
             '../../base/base.gyp:base_win64',
             '../../base/third_party/dynamic_annotations/dynamic_annotations.gyp:dynamic_annotations_win64',
+            '../../crypto/crypto.gyp:crypto_nacl_win64',
           ],
           'includes': [
             'mojo_edk_system_impl.gypi',
diff --git a/third_party/mojo/mojo_edk_system_impl.gypi b/third_party/mojo/mojo_edk_system_impl.gypi
index fc455ed..5bac8f3 100644
--- a/third_party/mojo/mojo_edk_system_impl.gypi
+++ b/third_party/mojo/mojo_edk_system_impl.gypi
@@ -60,7 +60,6 @@
     'src/mojo/edk/system/connection_identifier.h',
     'src/mojo/edk/system/connection_manager.cc',
     'src/mojo/edk/system/connection_manager.h',
-    'src/mojo/edk/system/connection_manager_messages.h',
     'src/mojo/edk/system/core.cc',
     'src/mojo/edk/system/core.h',
     'src/mojo/edk/system/data_pipe.cc',
@@ -102,8 +101,6 @@
     'src/mojo/edk/system/message_pipe_dispatcher.h',
     'src/mojo/edk/system/message_pipe_endpoint.cc',
     'src/mojo/edk/system/message_pipe_endpoint.h',
-    'src/mojo/edk/system/mutex.cc',
-    'src/mojo/edk/system/mutex.h',
     'src/mojo/edk/system/options_validation.h',
     'src/mojo/edk/system/platform_handle_dispatcher.cc',
     'src/mojo/edk/system/platform_handle_dispatcher.h',
@@ -125,7 +122,6 @@
     'src/mojo/edk/system/simple_dispatcher.h',
     'src/mojo/edk/system/slave_connection_manager.cc',
     'src/mojo/edk/system/slave_connection_manager.h',
-    'src/mojo/edk/system/thread_annotations.h',
     'src/mojo/edk/system/transport_data.cc',
     'src/mojo/edk/system/transport_data.h',
     'src/mojo/edk/system/unique_identifier.cc',
diff --git a/third_party/mojo/mojo_edk_tests.gyp b/third_party/mojo/mojo_edk_tests.gyp
index 2e47591..db1fc36 100644
--- a/third_party/mojo/mojo_edk_tests.gyp
+++ b/third_party/mojo/mojo_edk_tests.gyp
@@ -17,7 +17,6 @@
         # target on iOS due to the presence of the js targets, which cause v8
         # to be built.
         'mojo_message_pipe_perftests',
-        'mojo_public_bindings_perftests',
         'mojo_public_bindings_unittests',
         'mojo_public_environment_unittests',
         'mojo_public_system_perftests',
@@ -53,8 +52,6 @@
         'src/mojo/public/cpp/bindings/tests/handle_passing_unittest.cc',
         'src/mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc',
         'src/mojo/public/cpp/bindings/tests/map_unittest.cc',
-        'src/mojo/public/cpp/bindings/tests/message_queue.cc',
-        'src/mojo/public/cpp/bindings/tests/message_queue.h',
         'src/mojo/public/cpp/bindings/tests/request_response_unittest.cc',
         'src/mojo/public/cpp/bindings/tests/router_unittest.cc',
         'src/mojo/public/cpp/bindings/tests/sample_service_unittest.cc',
@@ -66,24 +63,6 @@
       ],
     },
     {
-      # GN version: //mojo/edk/test:mojo_public_bindings_perftests
-      'target_name': 'mojo_public_bindings_perftests',
-      'type': 'executable',
-      'dependencies': [
-        '../../testing/gtest.gyp:gtest',
-        'mojo_edk.gyp:mojo_run_all_unittests',
-        'mojo_public.gyp:mojo_cpp_bindings',
-        'mojo_public.gyp:mojo_environment_standalone',
-        'mojo_public.gyp:mojo_public_bindings_test_utils',
-        'mojo_public.gyp:mojo_public_test_interfaces',
-        'mojo_public.gyp:mojo_public_test_utils',
-        'mojo_public.gyp:mojo_utility',
-      ],
-      'sources': [
-        'src/mojo/public/cpp/bindings/tests/bindings_perftest.cc',
-      ],
-    },
-    {
       # GN version: //mojo/edk/test:mojo_public_environment_unittests
       'target_name': 'mojo_public_environment_unittests',
       'type': 'executable',
@@ -196,7 +175,6 @@
         'src/mojo/edk/system/message_pipe_test_utils.h',
         'src/mojo/edk/system/message_pipe_unittest.cc',
         'src/mojo/edk/system/multiprocess_message_pipe_unittest.cc',
-        'src/mojo/edk/system/mutex_unittest.cc',
         'src/mojo/edk/system/options_validation_unittest.cc',
         'src/mojo/edk/system/platform_handle_dispatcher_unittest.cc',
         'src/mojo/edk/system/raw_channel_unittest.cc',
@@ -209,7 +187,6 @@
         'src/mojo/edk/system/test_channel_endpoint_client.h',
         'src/mojo/edk/system/test_utils.cc',
         'src/mojo/edk/system/test_utils.h',
-        'src/mojo/edk/system/thread_annotations_unittest.cc',
         'src/mojo/edk/system/unique_identifier_unittest.cc',
         'src/mojo/edk/system/waiter_test_utils.cc',
         'src/mojo/edk/system/waiter_test_utils.h',
diff --git a/third_party/mojo/mojo_public.gyp b/third_party/mojo/mojo_public.gyp
index f5b8265..3f16424 100644
--- a/third_party/mojo/mojo_public.gyp
+++ b/third_party/mojo/mojo_public.gyp
@@ -104,6 +104,7 @@
         'src/mojo/public/cpp/bindings/array.h',
         'src/mojo/public/cpp/bindings/binding.h',
         'src/mojo/public/cpp/bindings/callback.h',
+        'src/mojo/public/cpp/bindings/error_handler.h',
         'src/mojo/public/cpp/bindings/interface_impl.h',
         'src/mojo/public/cpp/bindings/interface_ptr.h',
         'src/mojo/public/cpp/bindings/interface_request.h',
@@ -144,6 +145,8 @@
         'src/mojo/public/cpp/bindings/lib/message_header_validator.cc',
         'src/mojo/public/cpp/bindings/lib/message_header_validator.h',
         'src/mojo/public/cpp/bindings/lib/message_internal.h',
+        'src/mojo/public/cpp/bindings/lib/message_queue.cc',
+        'src/mojo/public/cpp/bindings/lib/message_queue.h',
         'src/mojo/public/cpp/bindings/lib/no_interface.cc',
         'src/mojo/public/cpp/bindings/lib/router.cc',
         'src/mojo/public/cpp/bindings/lib/router.h',
@@ -330,7 +333,6 @@
         'mojom_files': [
           'src/mojo/public/interfaces/bindings/tests/math_calculator.mojom',
           'src/mojo/public/interfaces/bindings/tests/no_module.mojom',
-          'src/mojo/public/interfaces/bindings/tests/ping_service.mojom',
           'src/mojo/public/interfaces/bindings/tests/rect.mojom',
           'src/mojo/public/interfaces/bindings/tests/regression_tests.mojom',
           'src/mojo/public/interfaces/bindings/tests/sample_factory.mojom',
diff --git a/third_party/mojo/src/mojo/edk/embedder/BUILD.gn b/third_party/mojo/src/mojo/edk/embedder/BUILD.gn
index b3144f0..c3e0d53 100644
--- a/third_party/mojo/src/mojo/edk/embedder/BUILD.gn
+++ b/third_party/mojo/src/mojo/edk/embedder/BUILD.gn
@@ -87,6 +87,7 @@ mojo_edk_source_set("platform") {
 
   deps = [
     "//base",
+    "//crypto",
   ]
 
   if (is_android) {
diff --git a/third_party/mojo/src/mojo/edk/embedder/embedder_unittest.cc b/third_party/mojo/src/mojo/edk/embedder/embedder_unittest.cc
index e9735b1..0d1f3d9 100644
--- a/third_party/mojo/src/mojo/edk/embedder/embedder_unittest.cc
+++ b/third_party/mojo/src/mojo/edk/embedder/embedder_unittest.cc
@@ -16,7 +16,6 @@
 #include "base/test/test_timeouts.h"
 #include "mojo/edk/embedder/platform_channel_pair.h"
 #include "mojo/edk/embedder/test_embedder.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/test_utils.h"
 #include "mojo/edk/test/multiprocess_test_helper.h"
 #include "mojo/edk/test/scoped_ipc_support.h"
@@ -181,7 +180,7 @@ class TestAsyncWaiter {
   TestAsyncWaiter() : event_(true, false), wait_result_(MOJO_RESULT_UNKNOWN) {}
 
   void Awake(MojoResult result) {
-    system::MutexLocker l(&wait_result_mutex_);
+    base::AutoLock l(wait_result_lock_);
     wait_result_ = result;
     event_.Signal();
   }
@@ -189,15 +188,15 @@ class TestAsyncWaiter {
   bool TryWait() { return event_.TimedWait(TestTimeouts::action_timeout()); }
 
   MojoResult wait_result() const {
-    system::MutexLocker l(&wait_result_mutex_);
+    base::AutoLock l(wait_result_lock_);
     return wait_result_;
   }
 
  private:
   base::WaitableEvent event_;
 
-  mutable system::Mutex wait_result_mutex_;
-  MojoResult wait_result_ MOJO_GUARDED_BY(wait_result_mutex_);
+  mutable base::Lock wait_result_lock_;
+  MojoResult wait_result_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(TestAsyncWaiter);
 };
diff --git a/third_party/mojo/src/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc b/third_party/mojo/src/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc
index c7b49c2..897929f 100644
--- a/third_party/mojo/src/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc
+++ b/third_party/mojo/src/mojo/edk/embedder/platform_channel_pair_posix_unittest.cc
@@ -15,7 +15,10 @@
 
 #include <deque>
 
+#include "base/files/file_path.h"
+#include "base/files/file_util.h"
 #include "base/files/scoped_file.h"
+#include "base/files/scoped_temp_dir.h"
 #include "base/logging.h"
 #include "mojo/edk/embedder/platform_channel_utils_posix.h"
 #include "mojo/edk/embedder/platform_handle.h"
@@ -125,6 +128,9 @@ TEST_F(PlatformChannelPairPosixTest, SendReceiveData) {
 }
 
 TEST_F(PlatformChannelPairPosixTest, SendReceiveFDs) {
+  base::ScopedTempDir temp_dir;
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+
   static const char kHello[] = "hello";
 
   PlatformChannelPair channel_pair;
@@ -144,7 +150,9 @@ TEST_F(PlatformChannelPairPosixTest, SendReceiveFDs) {
     const char c = '0' + (i % 10);
     ScopedPlatformHandleVectorPtr platform_handles(new PlatformHandleVector);
     for (size_t j = 1; j <= i; j++) {
-      base::ScopedFILE fp(tmpfile());
+      base::FilePath unused;
+      base::ScopedFILE fp(
+          base::CreateAndOpenTemporaryFileInDir(temp_dir.path(), &unused));
       ASSERT_TRUE(fp);
       ASSERT_EQ(j, fwrite(std::string(j, c).data(), 1, j, fp.get()));
       platform_handles->push_back(
@@ -186,6 +194,9 @@ TEST_F(PlatformChannelPairPosixTest, SendReceiveFDs) {
 }
 
 TEST_F(PlatformChannelPairPosixTest, AppendReceivedFDs) {
+  base::ScopedTempDir temp_dir;
+  ASSERT_TRUE(temp_dir.CreateUniqueTempDir());
+
   static const char kHello[] = "hello";
 
   PlatformChannelPair channel_pair;
@@ -195,7 +206,9 @@ TEST_F(PlatformChannelPairPosixTest, AppendReceivedFDs) {
   const std::string file_contents("hello world");
 
   {
-    base::ScopedFILE fp(tmpfile());
+    base::FilePath unused;
+    base::ScopedFILE fp(
+        base::CreateAndOpenTemporaryFileInDir(temp_dir.path(), &unused));
     ASSERT_TRUE(fp);
     ASSERT_EQ(file_contents.size(),
               fwrite(file_contents.data(), 1, file_contents.size(), fp.get()));
diff --git a/third_party/mojo/src/mojo/edk/embedder/simple_platform_support.cc b/third_party/mojo/src/mojo/edk/embedder/simple_platform_support.cc
index 4207120..5024087 100644
--- a/third_party/mojo/src/mojo/edk/embedder/simple_platform_support.cc
+++ b/third_party/mojo/src/mojo/edk/embedder/simple_platform_support.cc
@@ -4,7 +4,7 @@
 
 #include "mojo/edk/embedder/simple_platform_support.h"
 
-#include "base/rand_util.h"
+#include "crypto/random.h"
 #include "mojo/edk/embedder/simple_platform_shared_buffer.h"
 
 namespace mojo {
@@ -12,7 +12,7 @@ namespace embedder {
 
 void SimplePlatformSupport::GetCryptoRandomBytes(void* bytes,
                                                  size_t num_bytes) {
-  base::RandBytes(bytes, num_bytes);
+  crypto::RandBytes(bytes, num_bytes);
 }
 
 PlatformSharedBuffer* SimplePlatformSupport::CreateSharedBuffer(
diff --git a/third_party/mojo/src/mojo/edk/js/tests/js_to_cpp_tests.cc b/third_party/mojo/src/mojo/edk/js/tests/js_to_cpp_tests.cc
index c012daf..3675f97 100644
--- a/third_party/mojo/src/mojo/edk/js/tests/js_to_cpp_tests.cc
+++ b/third_party/mojo/src/mojo/edk/js/tests/js_to_cpp_tests.cc
@@ -14,7 +14,6 @@
 #include "mojo/edk/js/mojo_runner_delegate.h"
 #include "mojo/edk/js/tests/js_to_cpp.mojom.h"
 #include "mojo/edk/test/test_utils.h"
-#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/system/core.h"
 #include "mojo/public/cpp/system/macros.h"
 #include "testing/gtest/include/gtest/gtest.h"
diff --git a/third_party/mojo/src/mojo/edk/mojo_edk.gni b/third_party/mojo/src/mojo/edk/mojo_edk.gni
index 21ad315..b90462d 100644
--- a/third_party/mojo/src/mojo/edk/mojo_edk.gni
+++ b/third_party/mojo/src/mojo/edk/mojo_edk.gni
@@ -95,9 +95,3 @@ template("mojo_edk_source_set") {
     }
   }
 }
-
-# Build EDK things with static thread annotation analysis enabled.
-# TODO(vtl): Should we set this at a higher level?
-if (is_clang) {
-  cflags = [ "-Wthread-safety" ]
-}
diff --git a/third_party/mojo/src/mojo/edk/system/BUILD.gn b/third_party/mojo/src/mojo/edk/system/BUILD.gn
index 5dd2682..95ee992 100644
--- a/third_party/mojo/src/mojo/edk/system/BUILD.gn
+++ b/third_party/mojo/src/mojo/edk/system/BUILD.gn
@@ -82,8 +82,6 @@ component("system") {
     "message_pipe_dispatcher.h",
     "message_pipe_endpoint.cc",
     "message_pipe_endpoint.h",
-    "mutex.cc",
-    "mutex.h",
     "options_validation.h",
     "platform_handle_dispatcher.cc",
     "platform_handle_dispatcher.h",
@@ -105,7 +103,6 @@ component("system") {
     "simple_dispatcher.h",
     "slave_connection_manager.cc",
     "slave_connection_manager.h",
-    "thread_annotations.h",
     "transport_data.cc",
     "transport_data.h",
     "unique_identifier.cc",
@@ -192,7 +189,6 @@ test("mojo_system_unittests") {
     "message_pipe_test_utils.h",
     "message_pipe_unittest.cc",
     "multiprocess_message_pipe_unittest.cc",
-    "mutex_unittest.cc",
     "options_validation_unittest.cc",
     "platform_handle_dispatcher_unittest.cc",
     "raw_channel_unittest.cc",
@@ -203,7 +199,6 @@ test("mojo_system_unittests") {
     "simple_dispatcher_unittest.cc",
     "test_channel_endpoint_client.cc",
     "test_channel_endpoint_client.h",
-    "thread_annotations_unittest.cc",
     "unique_identifier_unittest.cc",
     "waiter_test_utils.cc",
     "waiter_test_utils.h",
diff --git a/third_party/mojo/src/mojo/edk/system/channel.cc b/third_party/mojo/src/mojo/edk/system/channel.cc
index 601ddb0..470956f 100644
--- a/third_party/mojo/src/mojo/edk/system/channel.cc
+++ b/third_party/mojo/src/mojo/edk/system/channel.cc
@@ -39,7 +39,7 @@ void Channel::Init(scoped_ptr<RawChannel> raw_channel) {
   DCHECK(creation_thread_checker_.CalledOnValidThread());
   DCHECK(raw_channel);
 
-  // No need to take |mutex_|, since this must be called before this object
+  // No need to take |lock_|, since this must be called before this object
   // becomes thread-safe.
   DCHECK(!is_running_);
   raw_channel_ = raw_channel.Pass();
@@ -50,7 +50,7 @@ void Channel::Init(scoped_ptr<RawChannel> raw_channel) {
 void Channel::SetChannelManager(ChannelManager* channel_manager) {
   DCHECK(channel_manager);
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   DCHECK(!is_shutting_down_);
   DCHECK(!channel_manager_);
   channel_manager_ = channel_manager;
@@ -61,7 +61,7 @@ void Channel::Shutdown() {
 
   IdToEndpointMap to_destroy;
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
     if (!is_running_)
       return;
 
@@ -91,7 +91,7 @@ void Channel::Shutdown() {
 }
 
 void Channel::WillShutdownSoon() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   is_shutting_down_ = true;
   channel_manager_ = nullptr;
 }
@@ -109,7 +109,7 @@ void Channel::SetBootstrapEndpointWithIds(
   DCHECK(endpoint);
 
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
 
     DLOG_IF(WARNING, is_shutting_down_)
         << "SetBootstrapEndpoint() while shutting down";
@@ -125,7 +125,7 @@ void Channel::SetBootstrapEndpointWithIds(
 }
 
 bool Channel::WriteMessage(scoped_ptr<MessageInTransit> message) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (!is_running_) {
     // TODO(vtl): I think this is probably not an error condition, but I should
     // think about it (and the shutdown sequence) more carefully.
@@ -138,7 +138,7 @@ bool Channel::WriteMessage(scoped_ptr<MessageInTransit> message) {
 }
 
 bool Channel::IsWriteBufferEmpty() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (!is_running_)
     return true;
   return raw_channel_->IsWriteBufferEmpty();
@@ -154,7 +154,7 @@ void Channel::DetachEndpoint(ChannelEndpoint* endpoint,
     return;  // Nothing to do.
 
   {
-    MutexLocker locker_(&mutex_);
+    base::AutoLock locker_(lock_);
     if (!is_running_)
       return;
 
@@ -247,7 +247,7 @@ scoped_refptr<IncomingEndpoint> Channel::DeserializeEndpoint(
   DVLOG_IF(2, !local_id.is_valid() || !local_id.is_remote())
       << "Attempt to get incoming endpoint for invalid ID " << local_id;
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
 
   auto it = incoming_endpoints_.find(local_id);
   if (it == incoming_endpoints_.end()) {
@@ -264,9 +264,6 @@ scoped_refptr<IncomingEndpoint> Channel::DeserializeEndpoint(
 }
 
 size_t Channel::GetSerializedPlatformHandleSize() const {
-  // TODO(vtl): Having to lock |mutex_| here is a bit unfortunate. Maybe we
-  // should get the size in |Init()| and cache it?
-  MutexLocker locker(&mutex_);
   return raw_channel_->GetSerializedPlatformHandleSize();
 }
 
@@ -306,7 +303,7 @@ void Channel::OnError(Error error) {
       DVLOG(1) << "RawChannel read error (shutdown)";
       break;
     case ERROR_READ_BROKEN: {
-      MutexLocker locker(&mutex_);
+      base::AutoLock locker(lock_);
       LOG_IF(ERROR, !is_shutting_down_)
           << "RawChannel read error (connection broken)";
       break;
@@ -343,7 +340,7 @@ void Channel::OnReadMessageForEndpoint(
 
   scoped_refptr<ChannelEndpoint> endpoint;
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
 
     // Since we own |raw_channel_|, and this method and |Shutdown()| should only
     // be called from the creation thread, |raw_channel_| should never be null
@@ -462,7 +459,7 @@ bool Channel::OnAttachAndRunEndpoint(ChannelEndpointId local_id,
 
   bool success = true;
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
 
     if (local_id_to_endpoint_map_.find(local_id) ==
         local_id_to_endpoint_map_.end()) {
@@ -493,7 +490,7 @@ bool Channel::OnRemoveEndpoint(ChannelEndpointId local_id,
 
   scoped_refptr<ChannelEndpoint> endpoint;
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
 
     IdToEndpointMap::iterator it = local_id_to_endpoint_map_.find(local_id);
     if (it == local_id_to_endpoint_map_.end()) {
@@ -529,7 +526,7 @@ bool Channel::OnRemoveEndpoint(ChannelEndpointId local_id,
 bool Channel::OnRemoveEndpointAck(ChannelEndpointId local_id) {
   DCHECK(creation_thread_checker_.CalledOnValidThread());
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
 
   IdToEndpointMap::iterator it = local_id_to_endpoint_map_.find(local_id);
   if (it == local_id_to_endpoint_map_.end()) {
@@ -572,7 +569,7 @@ ChannelEndpointId Channel::AttachAndRunEndpoint(
   ChannelEndpointId local_id;
   ChannelEndpointId remote_id;
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
 
     DLOG_IF(WARNING, is_shutting_down_)
         << "AttachAndRunEndpoint() while shutting down";
diff --git a/third_party/mojo/src/mojo/edk/system/channel.h b/third_party/mojo/src/mojo/edk/system/channel.h
index 9b7c3ae..015fa73 100644
--- a/third_party/mojo/src/mojo/edk/system/channel.h
+++ b/third_party/mojo/src/mojo/edk/system/channel.h
@@ -10,13 +10,13 @@
 #include "base/containers/hash_tables.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
 #include "base/threading/thread_checker.h"
 #include "mojo/edk/embedder/scoped_platform_handle.h"
 #include "mojo/edk/system/channel_endpoint.h"
 #include "mojo/edk/system/channel_endpoint_id.h"
 #include "mojo/edk/system/incoming_endpoint.h"
 #include "mojo/edk/system/message_in_transit.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/raw_channel.h"
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/c/system/types.h"
@@ -59,7 +59,7 @@ class MOJO_SYSTEM_IMPL_EXPORT Channel final
   // This must be called on the creation thread before any other methods are
   // called, and before references to this object are given to any other
   // threads. |raw_channel| should be uninitialized.
-  void Init(scoped_ptr<RawChannel> raw_channel) MOJO_NOT_THREAD_SAFE;
+  void Init(scoped_ptr<RawChannel> raw_channel);
 
   // Sets the channel manager associated with this channel. This should be set
   // at most once and only called before |WillShutdownSoon()| (and
@@ -220,51 +220,47 @@ class MOJO_SYSTEM_IMPL_EXPORT Channel final
   ChannelEndpointId AttachAndRunEndpoint(
       scoped_refptr<ChannelEndpoint> endpoint);
 
-  // Helper to send channel control messages. Returns true on success. Callable
-  // from any thread.
+  // Helper to send channel control messages. Returns true on success. Should be
+  // called *without* |lock_| held. Callable from any thread.
   bool SendControlMessage(MessageInTransit::Subtype subtype,
                           ChannelEndpointId source_id,
-                          ChannelEndpointId destination_id)
-      MOJO_LOCKS_EXCLUDED(mutex_);
+                          ChannelEndpointId destination_id);
 
   base::ThreadChecker creation_thread_checker_;
 
   embedder::PlatformSupport* const platform_support_;
 
   // Note: |ChannelEndpointClient|s (in particular, |MessagePipe|s) MUST NOT be
-  // used under |mutex_|. E.g., |mutex_| can only be acquired after
+  // used under |lock_|. E.g., |lock_| can only be acquired after
   // |MessagePipe::lock_|, never before. Thus to call into a
   // |ChannelEndpointClient|, a reference should be acquired from
-  // |local_id_to_endpoint_map_| under |mutex_| and then the lock released.
-  // TODO(vtl): Annotate the above rule using |MOJO_ACQUIRED_{BEFORE,AFTER}()|,
-  // once clang actually checks such annotations.
-  // https://github.com/domokit/mojo/issues/313
-  mutable Mutex mutex_;
-
-  scoped_ptr<RawChannel> raw_channel_ MOJO_GUARDED_BY(mutex_);
-  bool is_running_ MOJO_GUARDED_BY(mutex_);
+  // |local_id_to_endpoint_map_| under |lock_| and then the lock released.
+  base::Lock lock_;  // Protects the members below.
+
+  scoped_ptr<RawChannel> raw_channel_;
+  bool is_running_;
   // Set when |WillShutdownSoon()| is called.
-  bool is_shutting_down_ MOJO_GUARDED_BY(mutex_);
+  bool is_shutting_down_;
 
   // Has a reference to us.
-  ChannelManager* channel_manager_ MOJO_GUARDED_BY(mutex_);
+  ChannelManager* channel_manager_;
 
   using IdToEndpointMap =
       base::hash_map<ChannelEndpointId, scoped_refptr<ChannelEndpoint>>;
   // Map from local IDs to endpoints. If the endpoint is null, this means that
   // we're just waiting for the remove ack before removing the entry.
-  IdToEndpointMap local_id_to_endpoint_map_ MOJO_GUARDED_BY(mutex_);
+  IdToEndpointMap local_id_to_endpoint_map_;
   // Note: The IDs generated by this should be checked for existence before use.
-  LocalChannelEndpointIdGenerator local_id_generator_ MOJO_GUARDED_BY(mutex_);
+  LocalChannelEndpointIdGenerator local_id_generator_;
 
   using IdToIncomingEndpointMap =
       base::hash_map<ChannelEndpointId, scoped_refptr<IncomingEndpoint>>;
   // Map from local IDs to incoming endpoints (i.e., those received inside other
   // messages, but not yet claimed via |DeserializeEndpoint()|).
-  IdToIncomingEndpointMap incoming_endpoints_ MOJO_GUARDED_BY(mutex_);
+  IdToIncomingEndpointMap incoming_endpoints_;
   // TODO(vtl): We need to keep track of remote IDs (so that we don't collide
   // if/when we wrap).
-  RemoteChannelEndpointIdGenerator remote_id_generator_ MOJO_GUARDED_BY(mutex_);
+  RemoteChannelEndpointIdGenerator remote_id_generator_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(Channel);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/channel_endpoint.cc b/third_party/mojo/src/mojo/edk/system/channel_endpoint.cc
index 038de8d..113bbd58 100644
--- a/third_party/mojo/src/mojo/edk/system/channel_endpoint.cc
+++ b/third_party/mojo/src/mojo/edk/system/channel_endpoint.cc
@@ -29,7 +29,7 @@ ChannelEndpoint::ChannelEndpoint(ChannelEndpointClient* client,
 bool ChannelEndpoint::EnqueueMessage(scoped_ptr<MessageInTransit> message) {
   DCHECK(message);
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
 
   switch (channel_state_) {
     case ChannelState::NOT_YET_ATTACHED:
@@ -53,7 +53,7 @@ bool ChannelEndpoint::ReplaceClient(ChannelEndpointClient* client,
                                     unsigned client_port) {
   DCHECK(client);
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   DCHECK(client_);
   DCHECK(client != client_.get() || client_port != client_port_);
   client_ = client;
@@ -62,7 +62,7 @@ bool ChannelEndpoint::ReplaceClient(ChannelEndpointClient* client,
 }
 
 void ChannelEndpoint::DetachFromClient() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   DCHECK(client_);
   client_ = nullptr;
 
@@ -79,7 +79,7 @@ void ChannelEndpoint::AttachAndRun(Channel* channel,
   DCHECK(local_id.is_valid());
   DCHECK(remote_id.is_valid());
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   DCHECK(channel_state_ == ChannelState::NOT_YET_ATTACHED);
   DCHECK(!channel_);
   DCHECK(!local_id_.is_valid());
@@ -119,7 +119,7 @@ void ChannelEndpoint::DetachFromChannel() {
   scoped_refptr<ChannelEndpointClient> client;
   unsigned client_port = 0;
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
 
     if (client_) {
       // Take a ref, and call |OnDetachFromChannel()| outside the lock.
@@ -155,7 +155,7 @@ ChannelEndpoint::~ChannelEndpoint() {
 bool ChannelEndpoint::WriteMessageNoLock(scoped_ptr<MessageInTransit> message) {
   DCHECK(message);
 
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
 
   DCHECK(channel_);
   DCHECK(local_id_.is_valid());
@@ -187,7 +187,7 @@ void ChannelEndpoint::OnReadMessageForClient(
   // -- impose significant cost in the common case.)
   for (;;) {
     {
-      MutexLocker locker(&mutex_);
+      base::AutoLock locker(lock_);
       if (!channel_ || !client_) {
         // This isn't a failure per se. (It just means that, e.g., the other end
         // of the message point closed first.)
diff --git a/third_party/mojo/src/mojo/edk/system/channel_endpoint.h b/third_party/mojo/src/mojo/edk/system/channel_endpoint.h
index c70e66e..807b1a8b 100644
--- a/third_party/mojo/src/mojo/edk/system/channel_endpoint.h
+++ b/third_party/mojo/src/mojo/edk/system/channel_endpoint.h
@@ -7,9 +7,9 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
 #include "mojo/edk/system/channel_endpoint_id.h"
 #include "mojo/edk/system/message_in_transit_queue.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/cpp/system/macros.h"
 
@@ -85,7 +85,7 @@ class MessageInTransit;
 //         shouldn't receive any more messages for that message pipe endpoint
 //         (local ID), but it must wait for the endpoint to detach. (It can't
 //         do so without a race, since it can't call into the message pipe
-//         under |mutex_|.) [TODO(vtl): When I add remotely-allocated IDs,
+//         under |lock_|.) [TODO(vtl): When I add remotely-allocated IDs,
 //         we'll have to remove the |EndpointInfo| from
 //         |local_id_to_endpoint_info_map_| -- i.e., remove the local ID,
 //         since it's no longer valid and may be reused by the remote side --
@@ -162,18 +162,19 @@ class MOJO_SYSTEM_IMPL_EXPORT ChannelEndpoint final
   friend class base::RefCountedThreadSafe<ChannelEndpoint>;
   ~ChannelEndpoint();
 
-  bool WriteMessageNoLock(scoped_ptr<MessageInTransit> message)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  // Must be called with |lock_| held.
+  bool WriteMessageNoLock(scoped_ptr<MessageInTransit> message);
 
   // Helper for |OnReadMessage()|, handling messages for the client.
   void OnReadMessageForClient(scoped_ptr<MessageInTransit> message);
 
   // Resets |channel_| to null (and sets |channel_state_| to
   // |ChannelState::DETACHED|). This may only be called if |channel_| is
-  // non-null.
-  void ResetChannelNoLock() MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  // non-null. Must be called with |lock_| held.
+  void ResetChannelNoLock();
 
-  Mutex mutex_;
+  // Protects the members below.
+  base::Lock lock_;
 
   // |client_| must be valid whenever it is non-null. Before |*client_| gives up
   // its reference to this object, it must call |DetachFromClient()|.
@@ -181,17 +182,14 @@ class MOJO_SYSTEM_IMPL_EXPORT ChannelEndpoint final
   // |Channel| needs to keep the |MessagePipe| alive for the "proxy-proxy" case.
   // Possibly we'll be able to eliminate that case when we have full
   // multiprocess support.
-  // WARNING: |ChannelEndpointClient| methods must not be called under |mutex_|.
-  // Thus to make such a call, a reference must first be taken under |mutex_|
-  // and the lock released.
-  // TODO(vtl): Annotate the above rule using |MOJO_ACQUIRED_{BEFORE,AFTER}()|,
-  // once clang actually checks such annotations.
-  // https://github.com/domokit/mojo/issues/313
+  // WARNING: |ChannelEndpointClient| methods must not be called under |lock_|.
+  // Thus to make such a call, a reference must first be taken under |lock_| and
+  // the lock released.
   // WARNING: Beware of interactions with |ReplaceClient()|. By the time the
   // call is made, the client may have changed. This must be detected and dealt
   // with.
-  scoped_refptr<ChannelEndpointClient> client_ MOJO_GUARDED_BY(mutex_);
-  unsigned client_port_ MOJO_GUARDED_BY(mutex_);
+  scoped_refptr<ChannelEndpointClient> client_;
+  unsigned client_port_;
 
   // State with respect to interaction with the |Channel|.
   enum class ChannelState {
@@ -203,17 +201,17 @@ class MOJO_SYSTEM_IMPL_EXPORT ChannelEndpoint final
     // |DetachFromChannel()| has been called (|channel_| is null).
     DETACHED
   };
-  ChannelState channel_state_ MOJO_GUARDED_BY(mutex_);
+  ChannelState channel_state_;
   // |channel_| must be valid whenever it is non-null. Before |*channel_| gives
   // up its reference to this object, it must call |DetachFromChannel()|.
   // |local_id_| and |remote_id_| are valid if and only |channel_| is non-null.
-  Channel* channel_ MOJO_GUARDED_BY(mutex_);
-  ChannelEndpointId local_id_ MOJO_GUARDED_BY(mutex_);
-  ChannelEndpointId remote_id_ MOJO_GUARDED_BY(mutex_);
+  Channel* channel_;
+  ChannelEndpointId local_id_;
+  ChannelEndpointId remote_id_;
 
   // This queue is used before we're running on a channel and ready to send
   // messages to the channel.
-  MessageInTransitQueue channel_message_queue_ MOJO_GUARDED_BY(mutex_);
+  MessageInTransitQueue channel_message_queue_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(ChannelEndpoint);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/channel_manager.cc b/third_party/mojo/src/mojo/edk/system/channel_manager.cc
index a2e4bf9..711b4da 100644
--- a/third_party/mojo/src/mojo/edk/system/channel_manager.cc
+++ b/third_party/mojo/src/mojo/edk/system/channel_manager.cc
@@ -57,7 +57,7 @@ void ChannelManager::ShutdownOnIOThread() {
   // consistency.
   ChannelIdToChannelMap channels;
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
     channels.swap(channels_);
   }
 
@@ -110,7 +110,7 @@ scoped_refptr<MessagePipeDispatcher> ChannelManager::CreateChannel(
 }
 
 scoped_refptr<Channel> ChannelManager::GetChannel(ChannelId channel_id) const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   auto it = channels_.find(channel_id);
   DCHECK(it != channels_.end());
   return it->second;
@@ -123,7 +123,7 @@ void ChannelManager::WillShutdownChannel(ChannelId channel_id) {
 void ChannelManager::ShutdownChannelOnIOThread(ChannelId channel_id) {
   scoped_refptr<Channel> channel;
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
     auto it = channels_.find(channel_id);
     DCHECK(it != channels_.end());
     channel.swap(it->second);
@@ -138,7 +138,7 @@ void ChannelManager::ShutdownChannel(
     scoped_refptr<base::TaskRunner> callback_thread_task_runner) {
   scoped_refptr<Channel> channel;
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
     auto it = channels_.find(channel_id);
     DCHECK(it != channels_.end());
     channel.swap(it->second);
@@ -178,7 +178,7 @@ void ChannelManager::CreateChannelOnIOThreadHelper(
   channel->SetBootstrapEndpoint(bootstrap_channel_endpoint);
 
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
     CHECK(channels_.find(channel_id) == channels_.end());
     channels_[channel_id] = channel;
   }
diff --git a/third_party/mojo/src/mojo/edk/system/channel_manager.h b/third_party/mojo/src/mojo/edk/system/channel_manager.h
index 014c1b3..9a9c0e8 100644
--- a/third_party/mojo/src/mojo/edk/system/channel_manager.h
+++ b/third_party/mojo/src/mojo/edk/system/channel_manager.h
@@ -10,9 +10,9 @@
 #include "base/callback_forward.h"
 #include "base/containers/hash_tables.h"
 #include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
 #include "mojo/edk/embedder/scoped_platform_handle.h"
 #include "mojo/edk/system/channel_id.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace base {
@@ -135,15 +135,12 @@ class MOJO_SYSTEM_IMPL_EXPORT ChannelManager {
   const scoped_refptr<base::TaskRunner> io_thread_task_runner_;
   ConnectionManager* const connection_manager_;
 
-  // Note: |Channel| methods should not be called under |mutex_|.
-  // TODO(vtl): Annotate the above rule using |MOJO_ACQUIRED_{BEFORE,AFTER}()|,
-  // once clang actually checks such annotations.
-  // https://github.com/domokit/mojo/issues/313
-  mutable Mutex mutex_;
+  // Note: |Channel| methods should not be called under |lock_|.
+  mutable base::Lock lock_;  // Protects the members below.
 
   using ChannelIdToChannelMap =
       base::hash_map<ChannelId, scoped_refptr<Channel>>;
-  ChannelIdToChannelMap channels_ MOJO_GUARDED_BY(mutex_);
+  ChannelIdToChannelMap channels_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(ChannelManager);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/connection_manager.h b/third_party/mojo/src/mojo/edk/system/connection_manager.h
index 5923c75..c92a121 100644
--- a/third_party/mojo/src/mojo/edk/system/connection_manager.h
+++ b/third_party/mojo/src/mojo/edk/system/connection_manager.h
@@ -5,12 +5,9 @@
 #ifndef MOJO_EDK_SYSTEM_CONNECTION_MANAGER_H_
 #define MOJO_EDK_SYSTEM_CONNECTION_MANAGER_H_
 
-#include <ostream>
-
 #include "mojo/edk/system/connection_identifier.h"
 #include "mojo/edk/system/process_identifier.h"
 #include "mojo/edk/system/system_impl_export.h"
-#include "mojo/edk/system/thread_annotations.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace mojo {
@@ -62,23 +59,13 @@ namespace system {
 // slave).
 class MOJO_SYSTEM_IMPL_EXPORT ConnectionManager {
  public:
-  enum class Result {
-    FAILURE = 0,
-    SUCCESS,
-    // These results are used for |Connect()| (which also uses |FAILURE|, but
-    // not |SUCCESS|).
-    SUCCESS_CONNECT_SAME_PROCESS,
-    SUCCESS_CONNECT_NEW_CONNECTION,
-    SUCCESS_CONNECT_REUSE_CONNECTION
-  };
-
   virtual ~ConnectionManager() {}
 
   ConnectionIdentifier GenerateConnectionIdentifier();
 
   // Shuts down this connection manager. No other methods may be called after
   // this is (or while it is being) called.
-  virtual void Shutdown() MOJO_NOT_THREAD_SAFE = 0;
+  virtual void Shutdown() = 0;
 
   // TODO(vtl): Add a "get my own process identifier" method?
 
@@ -98,14 +85,14 @@ class MOJO_SYSTEM_IMPL_EXPORT ConnectionManager {
   virtual bool CancelConnect(const ConnectionIdentifier& connection_id) = 0;
 
   // Connects a pending connection; to be called only after both parties have
-  // called |AllowConnect()|. On success, |Result::SUCCESS_CONNECT_...| is
-  // returned and |peer_process_identifier| is set to an unique identifier for
-  // the peer process. In the case of |SUCCESS_CONNECT_SAME_PROCESS|,
-  // |*platform_handle| is set to a suitable native handle connecting the two
-  // parties.
-  virtual Result Connect(const ConnectionIdentifier& connection_id,
-                         ProcessIdentifier* peer_process_identifier,
-                         embedder::ScopedPlatformHandle* platform_handle) = 0;
+  // called |AllowConnect()|. On success, |peer_process_identifier| is set to an
+  // unique identifier for the peer process, and if the peer process is not the
+  // same as the calling process then |*platform_handle| is set to a suitable
+  // native handle connecting the two parties (if the two parties are the same
+  // process, then |*platform_handle| is reset to be invalid).
+  virtual bool Connect(const ConnectionIdentifier& connection_id,
+                       ProcessIdentifier* peer_process_identifier,
+                       embedder::ScopedPlatformHandle* platform_handle) = 0;
 
  protected:
   // |platform_support| must be valid and remain alive until after |Shutdown()|
@@ -119,13 +106,6 @@ class MOJO_SYSTEM_IMPL_EXPORT ConnectionManager {
   MOJO_DISALLOW_COPY_AND_ASSIGN(ConnectionManager);
 };
 
-// So logging macros and |DCHECK_EQ()|, etc. work.
-MOJO_SYSTEM_IMPL_EXPORT inline std::ostream& operator<<(
-    std::ostream& out,
-    ConnectionManager::Result result) {
-  return out << static_cast<int>(result);
-}
-
 }  // namespace system
 }  // namespace mojo
 
diff --git a/third_party/mojo/src/mojo/edk/system/connection_manager_unittest.cc b/third_party/mojo/src/mojo/edk/system/connection_manager_unittest.cc
index 20fa73e..cb22ef3 100644
--- a/third_party/mojo/src/mojo/edk/system/connection_manager_unittest.cc
+++ b/third_party/mojo/src/mojo/edk/system/connection_manager_unittest.cc
@@ -226,14 +226,12 @@ TEST_F(ConnectionManagerTest, BasicConnectSlaves) {
 
   ProcessIdentifier peer1 = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h1;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION,
-            slave1.Connect(connection_id, &peer1, &h1));
+  EXPECT_TRUE(slave1.Connect(connection_id, &peer1, &h1));
   EXPECT_EQ(slave2_id, peer1);
   EXPECT_TRUE(h1.is_valid());
   ProcessIdentifier peer2 = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h2;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION,
-            slave2.Connect(connection_id, &peer2, &h2));
+  EXPECT_TRUE(slave2.Connect(connection_id, &peer2, &h2));
   EXPECT_EQ(slave1_id, peer2);
   EXPECT_TRUE(h2.is_valid());
 
@@ -321,8 +319,7 @@ TEST_F(ConnectionManagerTest, SlaveCancelConnect) {
   EXPECT_TRUE(slave1.CancelConnect(connection_id));
   ProcessIdentifier peer2 = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h2;
-  EXPECT_EQ(ConnectionManager::Result::FAILURE,
-            slave2.Connect(connection_id, &peer2, &h2));
+  EXPECT_FALSE(slave2.Connect(connection_id, &peer2, &h2));
   EXPECT_EQ(kInvalidProcessIdentifier, peer2);
   EXPECT_FALSE(h2.is_valid());
 
@@ -364,8 +361,7 @@ TEST_F(ConnectionManagerTest, ErrorRemovePending) {
 
   ProcessIdentifier peer2 = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h2;
-  EXPECT_EQ(ConnectionManager::Result::FAILURE,
-            slave2.Connect(connection_id, &peer2, &h2));
+  EXPECT_FALSE(slave2.Connect(connection_id, &peer2, &h2));
   EXPECT_EQ(kInvalidProcessIdentifier, peer2);
   EXPECT_FALSE(h2.is_valid());
 
@@ -388,16 +384,16 @@ TEST_F(ConnectionManagerTest, ConnectSlaveToSelf) {
   EXPECT_TRUE(slave.AllowConnect(connection_id));
   EXPECT_TRUE(slave.AllowConnect(connection_id));
 
+  // Currently, the connect-to-self case is signalled by the master not sending
+  // back a handle.
   ProcessIdentifier peer1 = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h1;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_SAME_PROCESS,
-            slave.Connect(connection_id, &peer1, &h1));
+  EXPECT_TRUE(slave.Connect(connection_id, &peer1, &h1));
   EXPECT_EQ(slave_id, peer1);
   EXPECT_FALSE(h1.is_valid());
   ProcessIdentifier peer2 = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h2;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_SAME_PROCESS,
-            slave.Connect(connection_id, &peer2, &h2));
+  EXPECT_TRUE(slave.Connect(connection_id, &peer2, &h2));
   EXPECT_EQ(slave_id, peer2);
   EXPECT_FALSE(h2.is_valid());
 
@@ -429,36 +425,30 @@ TEST_F(ConnectionManagerTest, ConnectSlavesTwice) {
 
   ProcessIdentifier peer1 = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h1;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION,
-            slave1.Connect(connection_id, &peer1, &h1));
+  EXPECT_TRUE(slave1.Connect(connection_id, &peer1, &h1));
   EXPECT_EQ(slave2_id, peer1);
   ProcessIdentifier peer2 = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h2;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION,
-            slave2.Connect(connection_id, &peer2, &h2));
+  EXPECT_TRUE(slave2.Connect(connection_id, &peer2, &h2));
   EXPECT_EQ(slave1_id, peer2);
 
   EXPECT_TRUE(ArePlatformHandlesConnected(h1.get(), h2.get()));
 
-  // TODO(vtl): Currently, the master doesn't detect the case of connecting a
-  // pair of slaves that are already connected. (Doing so would require more
-  // careful tracking and is prone to races -- especially if we want slaves to
-  // be able to tear down no-longer-needed connections.) But the slaves should
-  // be able to do the tracking themselves (using the peer process identifiers).
+  // Currently, the master doesn't detect the case of connecting a pair of
+  // slaves that are already connected. (Doing so would require more careful
+  // tracking and is prone to races -- especially if we want slaves to be able
+  // to tear down no-longer-needed connections.) But the slaves should be able
+  // to do the tracking themselves (using the peer process identifiers).
   connection_id = master.GenerateConnectionIdentifier();
   EXPECT_TRUE(slave1.AllowConnect(connection_id));
   EXPECT_TRUE(slave2.AllowConnect(connection_id));
 
   h1.reset();
   h2.reset();
-  // TODO(vtl): FIXME -- this will break when I implemented
-  // SUCCESS_CONNECT_REUSE_CONNECTION.
   ProcessIdentifier second_peer2 = kInvalidProcessIdentifier;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION,
-            slave2.Connect(connection_id, &second_peer2, &h2));
+  EXPECT_TRUE(slave2.Connect(connection_id, &second_peer2, &h2));
   ProcessIdentifier second_peer1 = kInvalidProcessIdentifier;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION,
-            slave1.Connect(connection_id, &second_peer1, &h1));
+  EXPECT_TRUE(slave1.Connect(connection_id, &second_peer1, &h1));
 
   EXPECT_EQ(peer1, second_peer1);
   EXPECT_EQ(peer2, second_peer2);
@@ -486,14 +476,12 @@ TEST_F(ConnectionManagerTest, ConnectMasterToSlave) {
 
   ProcessIdentifier master_peer = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle master_h;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION,
-            master.Connect(connection_id, &master_peer, &master_h));
+  EXPECT_TRUE(master.Connect(connection_id, &master_peer, &master_h));
   EXPECT_EQ(slave_id, master_peer);
   EXPECT_TRUE(master_h.is_valid());
   ProcessIdentifier slave_peer = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle slave_h;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION,
-            slave.Connect(connection_id, &slave_peer, &slave_h));
+  EXPECT_TRUE(slave.Connect(connection_id, &slave_peer, &slave_h));
   EXPECT_EQ(kMasterProcessIdentifier, slave_peer);
   EXPECT_TRUE(slave_h.is_valid());
 
@@ -512,16 +500,16 @@ TEST_F(ConnectionManagerTest, ConnectMasterToSelf) {
   EXPECT_TRUE(master.AllowConnect(connection_id));
   EXPECT_TRUE(master.AllowConnect(connection_id));
 
+  // Currently, the connect-to-self case is signalled by the master not sending
+  // back a handle.
   ProcessIdentifier peer1 = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h1;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_SAME_PROCESS,
-            master.Connect(connection_id, &peer1, &h1));
+  EXPECT_TRUE(master.Connect(connection_id, &peer1, &h1));
   EXPECT_EQ(kMasterProcessIdentifier, peer1);
   EXPECT_FALSE(h1.is_valid());
   ProcessIdentifier peer2 = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h2;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_SAME_PROCESS,
-            master.Connect(connection_id, &peer2, &h2));
+  EXPECT_TRUE(master.Connect(connection_id, &peer2, &h2));
   EXPECT_EQ(kMasterProcessIdentifier, peer2);
   EXPECT_FALSE(h2.is_valid());
 
@@ -548,8 +536,7 @@ TEST_F(ConnectionManagerTest, MasterCancelConnect) {
   EXPECT_TRUE(master.CancelConnect(connection_id));
   ProcessIdentifier peer = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h;
-  EXPECT_EQ(ConnectionManager::Result::FAILURE,
-            slave.Connect(connection_id, &peer, &h));
+  EXPECT_FALSE(slave.Connect(connection_id, &peer, &h));
   EXPECT_EQ(kInvalidProcessIdentifier, peer);
   EXPECT_FALSE(h.is_valid());
 
@@ -586,8 +573,7 @@ TEST_F(ConnectionManagerTest, AddSlaveAndBootstrap) {
 
   embedder::ScopedPlatformHandle h1;
   ProcessIdentifier master_peer = kInvalidProcessIdentifier;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION,
-            master.Connect(connection_id, &master_peer, &h1));
+  EXPECT_TRUE(master.Connect(connection_id, &master_peer, &h1));
   EXPECT_EQ(slave_id, master_peer);
   EXPECT_TRUE(h1.is_valid());
 
@@ -599,8 +585,7 @@ TEST_F(ConnectionManagerTest, AddSlaveAndBootstrap) {
 
   ProcessIdentifier slave_peer = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle h2;
-  EXPECT_EQ(ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION,
-            slave.Connect(connection_id, &slave_peer, &h2));
+  EXPECT_TRUE(slave.Connect(connection_id, &slave_peer, &h2));
   EXPECT_EQ(kMasterProcessIdentifier, slave_peer);
 
   EXPECT_TRUE(ArePlatformHandlesConnected(h1.get(), h2.get()));
diff --git a/third_party/mojo/src/mojo/edk/system/core.cc b/third_party/mojo/src/mojo/edk/system/core.cc
index fbb6cf1..35d6614 100644
--- a/third_party/mojo/src/mojo/edk/system/core.cc
+++ b/third_party/mojo/src/mojo/edk/system/core.cc
@@ -86,7 +86,7 @@ Core::~Core() {
 }
 
 MojoHandle Core::AddDispatcher(const scoped_refptr<Dispatcher>& dispatcher) {
-  MutexLocker locker(&handle_table_mutex_);
+  base::AutoLock locker(handle_table_lock_);
   return handle_table_.AddDispatcher(dispatcher);
 }
 
@@ -94,7 +94,7 @@ scoped_refptr<Dispatcher> Core::GetDispatcher(MojoHandle handle) {
   if (handle == MOJO_HANDLE_INVALID)
     return nullptr;
 
-  MutexLocker locker(&handle_table_mutex_);
+  base::AutoLock locker(handle_table_lock_);
   return handle_table_.GetDispatcher(handle);
 }
 
@@ -103,7 +103,7 @@ MojoResult Core::GetAndRemoveDispatcher(MojoHandle handle,
   if (handle == MOJO_HANDLE_INVALID)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
-  MutexLocker locker(&handle_table_mutex_);
+  base::AutoLock locker(handle_table_lock_);
   return handle_table_.GetAndRemoveDispatcher(handle, dispatcher);
 }
 
@@ -130,7 +130,7 @@ MojoResult Core::Close(MojoHandle handle) {
 
   scoped_refptr<Dispatcher> dispatcher;
   {
-    MutexLocker locker(&handle_table_mutex_);
+    base::AutoLock locker(handle_table_lock_);
     MojoResult result =
         handle_table_.GetAndRemoveDispatcher(handle, &dispatcher);
     if (result != MOJO_RESULT_OK)
@@ -138,7 +138,7 @@ MojoResult Core::Close(MojoHandle handle) {
   }
 
   // The dispatcher doesn't have a say in being closed, but gets notified of it.
-  // Note: This is done outside of |handle_table_mutex_|. As a result, there's a
+  // Note: This is done outside of |handle_table_lock_|. As a result, there's a
   // race condition that the dispatcher must handle; see the comment in
   // |Dispatcher| in dispatcher.h.
   return dispatcher->Close();
@@ -211,7 +211,7 @@ MojoResult Core::CreateMessagePipe(
 
   std::pair<MojoHandle, MojoHandle> handle_pair;
   {
-    MutexLocker locker(&handle_table_mutex_);
+    base::AutoLock locker(handle_table_lock_);
     handle_pair = handle_table_.AddDispatcherPair(dispatcher0, dispatcher1);
   }
   if (handle_pair.first == MOJO_HANDLE_INVALID) {
@@ -276,7 +276,7 @@ MojoResult Core::WriteMessage(MojoHandle message_pipe_handle,
   // and mark the handles as busy. If the call succeeds, we then remove the
   // handles from the handle table.
   {
-    MutexLocker locker(&handle_table_mutex_);
+    base::AutoLock locker(handle_table_lock_);
     MojoResult result = handle_table_.MarkBusyAndStartTransport(
         message_pipe_handle, handles_reader.GetPointer(), num_handles,
         &transports);
@@ -293,7 +293,7 @@ MojoResult Core::WriteMessage(MojoHandle message_pipe_handle,
     transports[i].End();
 
   {
-    MutexLocker locker(&handle_table_mutex_);
+    base::AutoLock locker(handle_table_lock_);
     if (rv == MOJO_RESULT_OK) {
       handle_table_.RemoveBusyHandles(handles_reader.GetPointer(), num_handles);
     } else {
@@ -335,7 +335,7 @@ MojoResult Core::ReadMessage(MojoHandle message_pipe_handle,
       UserPointer<MojoHandle>::Writer handles_writer(handles,
                                                      dispatchers.size());
       {
-        MutexLocker locker(&handle_table_mutex_);
+        base::AutoLock locker(handle_table_lock_);
         success = handle_table_.AddDispatcherVector(
             dispatchers, handles_writer.GetPointer());
       }
@@ -377,7 +377,7 @@ MojoResult Core::CreateDataPipe(
 
   std::pair<MojoHandle, MojoHandle> handle_pair;
   {
-    MutexLocker locker(&handle_table_mutex_);
+    base::AutoLock locker(handle_table_lock_);
     handle_pair = handle_table_.AddDispatcherPair(producer_dispatcher,
                                                   consumer_dispatcher);
   }
@@ -539,7 +539,7 @@ MojoResult Core::MapBuffer(MojoHandle buffer_handle,
   DCHECK(mapping);
   void* address = mapping->GetBase();
   {
-    MutexLocker locker(&mapping_table_mutex_);
+    base::AutoLock locker(mapping_table_lock_);
     result = mapping_table_.AddMapping(mapping.Pass());
   }
   if (result != MOJO_RESULT_OK)
@@ -550,7 +550,7 @@ MojoResult Core::MapBuffer(MojoHandle buffer_handle,
 }
 
 MojoResult Core::UnmapBuffer(UserPointer<void> buffer) {
-  MutexLocker locker(&mapping_table_mutex_);
+  base::AutoLock locker(mapping_table_lock_);
   return mapping_table_.RemoveMapping(buffer.GetPointerValue());
 }
 
diff --git a/third_party/mojo/src/mojo/edk/system/core.h b/third_party/mojo/src/mojo/edk/system/core.h
index 4ed5ede..407a064 100644
--- a/third_party/mojo/src/mojo/edk/system/core.h
+++ b/third_party/mojo/src/mojo/edk/system/core.h
@@ -10,10 +10,10 @@
 #include "base/callback.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
 #include "mojo/edk/system/handle_table.h"
 #include "mojo/edk/system/mapping_table.h"
 #include "mojo/edk/system/memory.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/c/system/buffer.h"
 #include "mojo/public/c/system/data_pipe.h"
@@ -175,13 +175,13 @@ class MOJO_SYSTEM_IMPL_EXPORT Core {
 
   embedder::PlatformSupport* const platform_support_;
 
-  // TODO(vtl): |handle_table_mutex_| should be a reader-writer lock (if only we
+  // TODO(vtl): |handle_table_lock_| should be a reader-writer lock (if only we
   // had them).
-  Mutex handle_table_mutex_;
-  HandleTable handle_table_ MOJO_GUARDED_BY(handle_table_mutex_);
+  base::Lock handle_table_lock_;  // Protects |handle_table_|.
+  HandleTable handle_table_;
 
-  Mutex mapping_table_mutex_;
-  MappingTable mapping_table_ MOJO_GUARDED_BY(mapping_table_mutex_);
+  base::Lock mapping_table_lock_;  // Protects |mapping_table_|.
+  MappingTable mapping_table_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(Core);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/core_test_base.cc b/third_party/mojo/src/mojo/edk/system/core_test_base.cc
index 2552fd2..bfdcb1b 100644
--- a/third_party/mojo/src/mojo/edk/system/core_test_base.cc
+++ b/third_party/mojo/src/mojo/edk/system/core_test_base.cc
@@ -43,7 +43,7 @@ class MockDispatcher : public Dispatcher {
   // |Dispatcher| protected methods:
   void CloseImplNoLock() override {
     info_->IncrementCloseCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
   }
 
   MojoResult WriteMessageImplNoLock(
@@ -52,7 +52,7 @@ class MockDispatcher : public Dispatcher {
       std::vector<DispatcherTransport>* transports,
       MojoWriteMessageFlags /*flags*/) override {
     info_->IncrementWriteMessageCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
 
     if (num_bytes > GetConfiguration().max_message_num_bytes)
       return MOJO_RESULT_RESOURCE_EXHAUSTED;
@@ -69,7 +69,7 @@ class MockDispatcher : public Dispatcher {
                                    uint32_t* num_dispatchers,
                                    MojoReadMessageFlags /*flags*/) override {
     info_->IncrementReadMessageCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
 
     if (num_dispatchers) {
       *num_dispatchers = 1;
@@ -86,7 +86,7 @@ class MockDispatcher : public Dispatcher {
                                  UserPointer<uint32_t> /*num_bytes*/,
                                  MojoWriteDataFlags /*flags*/) override {
     info_->IncrementWriteDataCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
     return MOJO_RESULT_UNIMPLEMENTED;
   }
 
@@ -95,13 +95,13 @@ class MockDispatcher : public Dispatcher {
       UserPointer<uint32_t> /*buffer_num_bytes*/,
       MojoWriteDataFlags /*flags*/) override {
     info_->IncrementBeginWriteDataCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
     return MOJO_RESULT_UNIMPLEMENTED;
   }
 
   MojoResult EndWriteDataImplNoLock(uint32_t /*num_bytes_written*/) override {
     info_->IncrementEndWriteDataCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
     return MOJO_RESULT_UNIMPLEMENTED;
   }
 
@@ -109,7 +109,7 @@ class MockDispatcher : public Dispatcher {
                                 UserPointer<uint32_t> /*num_bytes*/,
                                 MojoReadDataFlags /*flags*/) override {
     info_->IncrementReadDataCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
     return MOJO_RESULT_UNIMPLEMENTED;
   }
 
@@ -117,13 +117,13 @@ class MockDispatcher : public Dispatcher {
                                      UserPointer<uint32_t> /*buffer_num_bytes*/,
                                      MojoReadDataFlags /*flags*/) override {
     info_->IncrementBeginReadDataCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
     return MOJO_RESULT_UNIMPLEMENTED;
   }
 
   MojoResult EndReadDataImplNoLock(uint32_t /*num_bytes_read*/) override {
     info_->IncrementEndReadDataCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
     return MOJO_RESULT_UNIMPLEMENTED;
   }
 
@@ -132,7 +132,7 @@ class MockDispatcher : public Dispatcher {
                                    uint32_t /*context*/,
                                    HandleSignalsState* signals_state) override {
     info_->IncrementAddAwakableCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
     if (signals_state)
       *signals_state = HandleSignalsState();
     if (info_->IsAddAwakableAllowed()) {
@@ -146,14 +146,14 @@ class MockDispatcher : public Dispatcher {
   void RemoveAwakableImplNoLock(Awakable* /*awakable*/,
                                 HandleSignalsState* signals_state) override {
     info_->IncrementRemoveAwakableCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
     if (signals_state)
       *signals_state = HandleSignalsState();
   }
 
   void CancelAllAwakablesNoLock() override {
     info_->IncrementCancelAllAwakablesCallCount();
-    mutex().AssertHeld();
+    lock().AssertAcquired();
   }
 
   scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock()
@@ -215,167 +215,167 @@ CoreTestBase_MockHandleInfo::~CoreTestBase_MockHandleInfo() {
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetCtorCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return ctor_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetDtorCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return dtor_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetCloseCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return close_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetWriteMessageCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return write_message_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetReadMessageCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return read_message_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetWriteDataCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return write_data_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetBeginWriteDataCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return begin_write_data_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetEndWriteDataCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return end_write_data_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetReadDataCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return read_data_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetBeginReadDataCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return begin_read_data_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetEndReadDataCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return end_read_data_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetAddAwakableCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return add_awakable_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetRemoveAwakableCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return remove_awakable_call_count_;
 }
 
 unsigned CoreTestBase_MockHandleInfo::GetCancelAllAwakablesCallCount() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return cancel_all_awakables_call_count_;
 }
 
 size_t CoreTestBase_MockHandleInfo::GetAddedAwakableSize() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return added_awakables_.size();
 }
 
 Awakable* CoreTestBase_MockHandleInfo::GetAddedAwakableAt(unsigned i) const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return added_awakables_[i];
 }
 
 void CoreTestBase_MockHandleInfo::IncrementCtorCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   ctor_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementDtorCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   dtor_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementCloseCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   close_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementWriteMessageCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   write_message_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementReadMessageCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   read_message_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementWriteDataCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   write_data_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementBeginWriteDataCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   begin_write_data_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementEndWriteDataCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   end_write_data_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementReadDataCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   read_data_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementBeginReadDataCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   begin_read_data_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementEndReadDataCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   end_read_data_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementAddAwakableCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   add_awakable_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementRemoveAwakableCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   remove_awakable_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::IncrementCancelAllAwakablesCallCount() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   cancel_all_awakables_call_count_++;
 }
 
 void CoreTestBase_MockHandleInfo::AllowAddAwakable(bool alllow) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   add_awakable_allowed_ = alllow;
 }
 
 bool CoreTestBase_MockHandleInfo::IsAddAwakableAllowed() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return add_awakable_allowed_;
 }
 
 void CoreTestBase_MockHandleInfo::AwakableWasAdded(Awakable* awakable) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   added_awakables_.push_back(awakable);
 }
 
diff --git a/third_party/mojo/src/mojo/edk/system/core_test_base.h b/third_party/mojo/src/mojo/edk/system/core_test_base.h
index e2375cd..ce32918 100644
--- a/third_party/mojo/src/mojo/edk/system/core_test_base.h
+++ b/third_party/mojo/src/mojo/edk/system/core_test_base.h
@@ -5,8 +5,8 @@
 #ifndef MOJO_EDK_SYSTEM_CORE_TEST_BASE_H_
 #define MOJO_EDK_SYSTEM_CORE_TEST_BASE_H_
 
+#include "base/synchronization/lock.h"
 #include "mojo/edk/embedder/simple_platform_support.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/public/c/system/types.h"
 #include "mojo/public/cpp/system/macros.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -88,24 +88,24 @@ class CoreTestBase_MockHandleInfo {
   void AwakableWasAdded(Awakable*);
 
  private:
-  mutable Mutex mutex_;
-  unsigned ctor_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned dtor_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned close_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned write_message_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned read_message_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned write_data_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned begin_write_data_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned end_write_data_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned read_data_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned begin_read_data_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned end_read_data_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned add_awakable_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned remove_awakable_call_count_ MOJO_GUARDED_BY(mutex_);
-  unsigned cancel_all_awakables_call_count_ MOJO_GUARDED_BY(mutex_);
-
-  bool add_awakable_allowed_ MOJO_GUARDED_BY(mutex_);
-  std::vector<Awakable*> added_awakables_ MOJO_GUARDED_BY(mutex_);
+  mutable base::Lock lock_;  // Protects the following members.
+  unsigned ctor_call_count_;
+  unsigned dtor_call_count_;
+  unsigned close_call_count_;
+  unsigned write_message_call_count_;
+  unsigned read_message_call_count_;
+  unsigned write_data_call_count_;
+  unsigned begin_write_data_call_count_;
+  unsigned end_write_data_call_count_;
+  unsigned read_data_call_count_;
+  unsigned begin_read_data_call_count_;
+  unsigned end_read_data_call_count_;
+  unsigned add_awakable_call_count_;
+  unsigned remove_awakable_call_count_;
+  unsigned cancel_all_awakables_call_count_;
+
+  bool add_awakable_allowed_;
+  std::vector<Awakable*> added_awakables_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(CoreTestBase_MockHandleInfo);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/data_pipe_consumer_dispatcher.cc b/third_party/mojo/src/mojo/edk/system/data_pipe_consumer_dispatcher.cc
index 5a1bafb..ac917d9 100644
--- a/third_party/mojo/src/mojo/edk/system/data_pipe_consumer_dispatcher.cc
+++ b/third_party/mojo/src/mojo/edk/system/data_pipe_consumer_dispatcher.cc
@@ -35,11 +35,6 @@ DataPipeConsumerDispatcher::Deserialize(Channel* channel,
   return dispatcher;
 }
 
-DataPipe* DataPipeConsumerDispatcher::GetDataPipeForTest() {
-  MutexLocker locker(&mutex());
-  return data_pipe_.get();
-}
-
 DataPipeConsumerDispatcher::DataPipeConsumerDispatcher() {
 }
 
@@ -49,19 +44,19 @@ DataPipeConsumerDispatcher::~DataPipeConsumerDispatcher() {
 }
 
 void DataPipeConsumerDispatcher::CancelAllAwakablesNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   data_pipe_->ConsumerCancelAllAwakables();
 }
 
 void DataPipeConsumerDispatcher::CloseImplNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   data_pipe_->ConsumerClose();
   data_pipe_ = nullptr;
 }
 
 scoped_refptr<Dispatcher>
 DataPipeConsumerDispatcher::CreateEquivalentDispatcherAndCloseImplNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   scoped_refptr<DataPipeConsumerDispatcher> rv = Create();
   rv->Init(data_pipe_);
@@ -73,7 +68,7 @@ MojoResult DataPipeConsumerDispatcher::ReadDataImplNoLock(
     UserPointer<void> elements,
     UserPointer<uint32_t> num_bytes,
     MojoReadDataFlags flags) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   if ((flags & MOJO_READ_DATA_FLAG_DISCARD)) {
     // These flags are mutally exclusive.
@@ -104,7 +99,7 @@ MojoResult DataPipeConsumerDispatcher::BeginReadDataImplNoLock(
     UserPointer<const void*> buffer,
     UserPointer<uint32_t> buffer_num_bytes,
     MojoReadDataFlags flags) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   // These flags may not be used in two-phase mode.
   if ((flags & MOJO_READ_DATA_FLAG_DISCARD) ||
@@ -117,14 +112,14 @@ MojoResult DataPipeConsumerDispatcher::BeginReadDataImplNoLock(
 
 MojoResult DataPipeConsumerDispatcher::EndReadDataImplNoLock(
     uint32_t num_bytes_read) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   return data_pipe_->ConsumerEndReadData(num_bytes_read);
 }
 
 HandleSignalsState DataPipeConsumerDispatcher::GetHandleSignalsStateImplNoLock()
     const {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return data_pipe_->ConsumerGetHandleSignalsState();
 }
 
@@ -133,7 +128,7 @@ MojoResult DataPipeConsumerDispatcher::AddAwakableImplNoLock(
     MojoHandleSignals signals,
     uint32_t context,
     HandleSignalsState* signals_state) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return data_pipe_->ConsumerAddAwakable(awakable, signals, context,
                                          signals_state);
 }
@@ -141,7 +136,7 @@ MojoResult DataPipeConsumerDispatcher::AddAwakableImplNoLock(
 void DataPipeConsumerDispatcher::RemoveAwakableImplNoLock(
     Awakable* awakable,
     HandleSignalsState* signals_state) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   data_pipe_->ConsumerRemoveAwakable(awakable, signals_state);
 }
 
@@ -167,7 +162,7 @@ bool DataPipeConsumerDispatcher::EndSerializeAndCloseImplNoLock(
 }
 
 bool DataPipeConsumerDispatcher::IsBusyNoLock() const {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return data_pipe_->ConsumerIsBusy();
 }
 
diff --git a/third_party/mojo/src/mojo/edk/system/data_pipe_consumer_dispatcher.h b/third_party/mojo/src/mojo/edk/system/data_pipe_consumer_dispatcher.h
index 29df228e..7d8b5ee 100644
--- a/third_party/mojo/src/mojo/edk/system/data_pipe_consumer_dispatcher.h
+++ b/third_party/mojo/src/mojo/edk/system/data_pipe_consumer_dispatcher.h
@@ -26,7 +26,7 @@ class MOJO_SYSTEM_IMPL_EXPORT DataPipeConsumerDispatcher final
   }
 
   // Must be called before any other methods.
-  void Init(scoped_refptr<DataPipe> data_pipe) MOJO_NOT_THREAD_SAFE;
+  void Init(scoped_refptr<DataPipe> data_pipe);
 
   // |Dispatcher| public methods:
   Type GetType() const override;
@@ -37,7 +37,7 @@ class MOJO_SYSTEM_IMPL_EXPORT DataPipeConsumerDispatcher final
   Deserialize(Channel* channel, const void* source, size_t size);
 
   // Get access to the |DataPipe| for testing.
-  DataPipe* GetDataPipeForTest();
+  DataPipe* GetDataPipeForTest() { return data_pipe_.get(); }
 
  private:
   DataPipeConsumerDispatcher();
@@ -64,18 +64,16 @@ class MOJO_SYSTEM_IMPL_EXPORT DataPipeConsumerDispatcher final
                                 HandleSignalsState* signals_state) override;
   void StartSerializeImplNoLock(Channel* channel,
                                 size_t* max_size,
-                                size_t* max_platform_handles) override
-      MOJO_NOT_THREAD_SAFE;
+                                size_t* max_platform_handles) override;
   bool EndSerializeAndCloseImplNoLock(
       Channel* channel,
       void* destination,
       size_t* actual_size,
-      embedder::PlatformHandleVector* platform_handles) override
-      MOJO_NOT_THREAD_SAFE;
+      embedder::PlatformHandleVector* platform_handles) override;
   bool IsBusyNoLock() const override;
 
-  // This will be null if closed.
-  scoped_refptr<DataPipe> data_pipe_ MOJO_GUARDED_BY(mutex());
+  // Protected by |lock()|:
+  scoped_refptr<DataPipe> data_pipe_;  // This will be null if closed.
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(DataPipeConsumerDispatcher);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/data_pipe_impl_unittest.cc b/third_party/mojo/src/mojo/edk/system/data_pipe_impl_unittest.cc
index 3b0470b..2846f8d 100644
--- a/third_party/mojo/src/mojo/edk/system/data_pipe_impl_unittest.cc
+++ b/third_party/mojo/src/mojo/edk/system/data_pipe_impl_unittest.cc
@@ -1647,7 +1647,7 @@ TYPED_TEST(DataPipeImplTest, AllOrNone) {
   this->ConsumerClose();
 }
 
-TYPED_TEST(DataPipeImplTest, TwoPhaseAllOrNone) {
+TYPED_TEST(DataPipeImplTest, DISABLED_TwoPhaseAllOrNone) {
   const MojoCreateDataPipeOptions options = {
       kSizeOfOptions,                           // |struct_size|.
       MOJO_CREATE_DATA_PIPE_OPTIONS_FLAG_NONE,  // |flags|.
diff --git a/third_party/mojo/src/mojo/edk/system/data_pipe_producer_dispatcher.cc b/third_party/mojo/src/mojo/edk/system/data_pipe_producer_dispatcher.cc
index ddb8b9f..88190cf 100644
--- a/third_party/mojo/src/mojo/edk/system/data_pipe_producer_dispatcher.cc
+++ b/third_party/mojo/src/mojo/edk/system/data_pipe_producer_dispatcher.cc
@@ -35,11 +35,6 @@ DataPipeProducerDispatcher::Deserialize(Channel* channel,
   return dispatcher;
 }
 
-DataPipe* DataPipeProducerDispatcher::GetDataPipeForTest() {
-  MutexLocker locker(&mutex());
-  return data_pipe_.get();
-}
-
 DataPipeProducerDispatcher::DataPipeProducerDispatcher() {
 }
 
@@ -49,19 +44,19 @@ DataPipeProducerDispatcher::~DataPipeProducerDispatcher() {
 }
 
 void DataPipeProducerDispatcher::CancelAllAwakablesNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   data_pipe_->ProducerCancelAllAwakables();
 }
 
 void DataPipeProducerDispatcher::CloseImplNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   data_pipe_->ProducerClose();
   data_pipe_ = nullptr;
 }
 
 scoped_refptr<Dispatcher>
 DataPipeProducerDispatcher::CreateEquivalentDispatcherAndCloseImplNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   scoped_refptr<DataPipeProducerDispatcher> rv = Create();
   rv->Init(data_pipe_);
@@ -73,7 +68,7 @@ MojoResult DataPipeProducerDispatcher::WriteDataImplNoLock(
     UserPointer<const void> elements,
     UserPointer<uint32_t> num_bytes,
     MojoWriteDataFlags flags) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return data_pipe_->ProducerWriteData(
       elements, num_bytes, (flags & MOJO_WRITE_DATA_FLAG_ALL_OR_NONE));
 }
@@ -82,7 +77,7 @@ MojoResult DataPipeProducerDispatcher::BeginWriteDataImplNoLock(
     UserPointer<void*> buffer,
     UserPointer<uint32_t> buffer_num_bytes,
     MojoWriteDataFlags flags) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   return data_pipe_->ProducerBeginWriteData(
       buffer, buffer_num_bytes, (flags & MOJO_WRITE_DATA_FLAG_ALL_OR_NONE));
@@ -90,14 +85,14 @@ MojoResult DataPipeProducerDispatcher::BeginWriteDataImplNoLock(
 
 MojoResult DataPipeProducerDispatcher::EndWriteDataImplNoLock(
     uint32_t num_bytes_written) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   return data_pipe_->ProducerEndWriteData(num_bytes_written);
 }
 
 HandleSignalsState DataPipeProducerDispatcher::GetHandleSignalsStateImplNoLock()
     const {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return data_pipe_->ProducerGetHandleSignalsState();
 }
 
@@ -106,7 +101,7 @@ MojoResult DataPipeProducerDispatcher::AddAwakableImplNoLock(
     MojoHandleSignals signals,
     uint32_t context,
     HandleSignalsState* signals_state) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return data_pipe_->ProducerAddAwakable(awakable, signals, context,
                                          signals_state);
 }
@@ -114,7 +109,7 @@ MojoResult DataPipeProducerDispatcher::AddAwakableImplNoLock(
 void DataPipeProducerDispatcher::RemoveAwakableImplNoLock(
     Awakable* awakable,
     HandleSignalsState* signals_state) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   data_pipe_->ProducerRemoveAwakable(awakable, signals_state);
 }
 
@@ -140,7 +135,7 @@ bool DataPipeProducerDispatcher::EndSerializeAndCloseImplNoLock(
 }
 
 bool DataPipeProducerDispatcher::IsBusyNoLock() const {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return data_pipe_->ProducerIsBusy();
 }
 
diff --git a/third_party/mojo/src/mojo/edk/system/data_pipe_producer_dispatcher.h b/third_party/mojo/src/mojo/edk/system/data_pipe_producer_dispatcher.h
index 7ce5156..86697fe 100644
--- a/third_party/mojo/src/mojo/edk/system/data_pipe_producer_dispatcher.h
+++ b/third_party/mojo/src/mojo/edk/system/data_pipe_producer_dispatcher.h
@@ -26,7 +26,7 @@ class MOJO_SYSTEM_IMPL_EXPORT DataPipeProducerDispatcher final
   }
 
   // Must be called before any other methods.
-  void Init(scoped_refptr<DataPipe> data_pipe) MOJO_NOT_THREAD_SAFE;
+  void Init(scoped_refptr<DataPipe> data_pipe);
 
   // |Dispatcher| public methods:
   Type GetType() const override;
@@ -37,7 +37,7 @@ class MOJO_SYSTEM_IMPL_EXPORT DataPipeProducerDispatcher final
   Deserialize(Channel* channel, const void* source, size_t size);
 
   // Get access to the |DataPipe| for testing.
-  DataPipe* GetDataPipeForTest();
+  DataPipe* GetDataPipeForTest() { return data_pipe_.get(); }
 
  private:
   DataPipeProducerDispatcher();
@@ -64,18 +64,16 @@ class MOJO_SYSTEM_IMPL_EXPORT DataPipeProducerDispatcher final
                                 HandleSignalsState* signals_state) override;
   void StartSerializeImplNoLock(Channel* channel,
                                 size_t* max_size,
-                                size_t* max_platform_handles) override
-      MOJO_NOT_THREAD_SAFE;
+                                size_t* max_platform_handles) override;
   bool EndSerializeAndCloseImplNoLock(
       Channel* channel,
       void* destination,
       size_t* actual_size,
-      embedder::PlatformHandleVector* platform_handles) override
-      MOJO_NOT_THREAD_SAFE;
+      embedder::PlatformHandleVector* platform_handles) override;
   bool IsBusyNoLock() const override;
 
-  // This will be null if closed.
-  scoped_refptr<DataPipe> data_pipe_ MOJO_GUARDED_BY(mutex());
+  // Protected by |lock()|:
+  scoped_refptr<DataPipe> data_pipe_;  // This will be null if closed.
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(DataPipeProducerDispatcher);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/dispatcher.cc b/third_party/mojo/src/mojo/edk/system/dispatcher.cc
index ad362fe..24f2c26 100644
--- a/third_party/mojo/src/mojo/edk/system/dispatcher.cc
+++ b/third_party/mojo/src/mojo/edk/system/dispatcher.cc
@@ -26,18 +26,16 @@ DispatcherTransport DispatcherTryStartTransport(Dispatcher* dispatcher) {
 
 // Dispatcher ------------------------------------------------------------------
 
-// TODO(vtl): The thread-safety analyzer isn't smart enough to deal with the
-// fact that we give up if |TryLock()| fails.
 // static
 DispatcherTransport Dispatcher::HandleTableAccess::TryStartTransport(
-    Dispatcher* dispatcher) MOJO_NO_THREAD_SAFETY_ANALYSIS {
+    Dispatcher* dispatcher) {
   DCHECK(dispatcher);
 
-  if (!dispatcher->mutex_.TryLock())
+  if (!dispatcher->lock_.Try())
     return DispatcherTransport();
 
   // We shouldn't race with things that close dispatchers, since closing can
-  // only take place either under |handle_table_mutex_| or when the handle is
+  // only take place either under |handle_table_lock_| or when the handle is
   // marked as busy.
   DCHECK(!dispatcher->is_closed_);
 
@@ -98,7 +96,7 @@ scoped_refptr<Dispatcher> Dispatcher::TransportDataAccess::Deserialize(
 }
 
 MojoResult Dispatcher::Close() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -115,7 +113,7 @@ MojoResult Dispatcher::WriteMessage(
          (transports->size() > 0 &&
           transports->size() < GetConfiguration().max_message_num_handles));
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -130,7 +128,7 @@ MojoResult Dispatcher::ReadMessage(UserPointer<void> bytes,
   DCHECK(!num_dispatchers || *num_dispatchers == 0 ||
          (dispatchers && dispatchers->empty()));
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -141,7 +139,7 @@ MojoResult Dispatcher::ReadMessage(UserPointer<void> bytes,
 MojoResult Dispatcher::WriteData(UserPointer<const void> elements,
                                  UserPointer<uint32_t> num_bytes,
                                  MojoWriteDataFlags flags) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -151,7 +149,7 @@ MojoResult Dispatcher::WriteData(UserPointer<const void> elements,
 MojoResult Dispatcher::BeginWriteData(UserPointer<void*> buffer,
                                       UserPointer<uint32_t> buffer_num_bytes,
                                       MojoWriteDataFlags flags) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -159,7 +157,7 @@ MojoResult Dispatcher::BeginWriteData(UserPointer<void*> buffer,
 }
 
 MojoResult Dispatcher::EndWriteData(uint32_t num_bytes_written) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -169,7 +167,7 @@ MojoResult Dispatcher::EndWriteData(uint32_t num_bytes_written) {
 MojoResult Dispatcher::ReadData(UserPointer<void> elements,
                                 UserPointer<uint32_t> num_bytes,
                                 MojoReadDataFlags flags) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -179,7 +177,7 @@ MojoResult Dispatcher::ReadData(UserPointer<void> elements,
 MojoResult Dispatcher::BeginReadData(UserPointer<const void*> buffer,
                                      UserPointer<uint32_t> buffer_num_bytes,
                                      MojoReadDataFlags flags) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -187,7 +185,7 @@ MojoResult Dispatcher::BeginReadData(UserPointer<const void*> buffer,
 }
 
 MojoResult Dispatcher::EndReadData(uint32_t num_bytes_read) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -197,7 +195,7 @@ MojoResult Dispatcher::EndReadData(uint32_t num_bytes_read) {
 MojoResult Dispatcher::DuplicateBufferHandle(
     UserPointer<const MojoDuplicateBufferHandleOptions> options,
     scoped_refptr<Dispatcher>* new_dispatcher) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -209,7 +207,7 @@ MojoResult Dispatcher::MapBuffer(
     uint64_t num_bytes,
     MojoMapBufferFlags flags,
     scoped_ptr<embedder::PlatformSharedBufferMapping>* mapping) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return MOJO_RESULT_INVALID_ARGUMENT;
 
@@ -217,7 +215,7 @@ MojoResult Dispatcher::MapBuffer(
 }
 
 HandleSignalsState Dispatcher::GetHandleSignalsState() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_)
     return HandleSignalsState();
 
@@ -228,7 +226,7 @@ MojoResult Dispatcher::AddAwakable(Awakable* awakable,
                                    MojoHandleSignals signals,
                                    uint32_t context,
                                    HandleSignalsState* signals_state) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_) {
     if (signals_state)
       *signals_state = HandleSignalsState();
@@ -240,7 +238,7 @@ MojoResult Dispatcher::AddAwakable(Awakable* awakable,
 
 void Dispatcher::RemoveAwakable(Awakable* awakable,
                                 HandleSignalsState* handle_signals_state) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (is_closed_) {
     if (handle_signals_state)
       *handle_signals_state = HandleSignalsState();
@@ -259,14 +257,14 @@ Dispatcher::~Dispatcher() {
 }
 
 void Dispatcher::CancelAllAwakablesNoLock() {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(is_closed_);
   // By default, waiting isn't supported. Only dispatchers that can be waited on
   // will do something nontrivial.
 }
 
 void Dispatcher::CloseImplNoLock() {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(is_closed_);
   // This may not need to do anything. Dispatchers should override this to do
   // any actual close-time cleanup necessary.
@@ -277,7 +275,7 @@ MojoResult Dispatcher::WriteMessageImplNoLock(
     uint32_t /*num_bytes*/,
     std::vector<DispatcherTransport>* /*transports*/,
     MojoWriteMessageFlags /*flags*/) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for message pipe dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
@@ -289,7 +287,7 @@ MojoResult Dispatcher::ReadMessageImplNoLock(
     DispatcherVector* /*dispatchers*/,
     uint32_t* /*num_dispatchers*/,
     MojoReadMessageFlags /*flags*/) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for message pipe dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
@@ -298,7 +296,7 @@ MojoResult Dispatcher::ReadMessageImplNoLock(
 MojoResult Dispatcher::WriteDataImplNoLock(UserPointer<const void> /*elements*/,
                                            UserPointer<uint32_t> /*num_bytes*/,
                                            MojoWriteDataFlags /*flags*/) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for data pipe dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
@@ -308,14 +306,14 @@ MojoResult Dispatcher::BeginWriteDataImplNoLock(
     UserPointer<void*> /*buffer*/,
     UserPointer<uint32_t> /*buffer_num_bytes*/,
     MojoWriteDataFlags /*flags*/) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for data pipe dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
 }
 
 MojoResult Dispatcher::EndWriteDataImplNoLock(uint32_t /*num_bytes_written*/) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for data pipe dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
@@ -324,7 +322,7 @@ MojoResult Dispatcher::EndWriteDataImplNoLock(uint32_t /*num_bytes_written*/) {
 MojoResult Dispatcher::ReadDataImplNoLock(UserPointer<void> /*elements*/,
                                           UserPointer<uint32_t> /*num_bytes*/,
                                           MojoReadDataFlags /*flags*/) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for data pipe dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
@@ -334,14 +332,14 @@ MojoResult Dispatcher::BeginReadDataImplNoLock(
     UserPointer<const void*> /*buffer*/,
     UserPointer<uint32_t> /*buffer_num_bytes*/,
     MojoReadDataFlags /*flags*/) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for data pipe dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
 }
 
 MojoResult Dispatcher::EndReadDataImplNoLock(uint32_t /*num_bytes_read*/) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for data pipe dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
@@ -350,7 +348,7 @@ MojoResult Dispatcher::EndReadDataImplNoLock(uint32_t /*num_bytes_read*/) {
 MojoResult Dispatcher::DuplicateBufferHandleImplNoLock(
     UserPointer<const MojoDuplicateBufferHandleOptions> /*options*/,
     scoped_refptr<Dispatcher>* /*new_dispatcher*/) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for buffer dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
@@ -361,14 +359,14 @@ MojoResult Dispatcher::MapBufferImplNoLock(
     uint64_t /*num_bytes*/,
     MojoMapBufferFlags /*flags*/,
     scoped_ptr<embedder::PlatformSharedBufferMapping>* /*mapping*/) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, not supported. Only needed for buffer dispatchers.
   return MOJO_RESULT_INVALID_ARGUMENT;
 }
 
 HandleSignalsState Dispatcher::GetHandleSignalsStateImplNoLock() const {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, waiting isn't supported. Only dispatchers that can be waited on
   // will do something nontrivial.
@@ -380,7 +378,7 @@ MojoResult Dispatcher::AddAwakableImplNoLock(
     MojoHandleSignals /*signals*/,
     uint32_t /*context*/,
     HandleSignalsState* signals_state) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, waiting isn't supported. Only dispatchers that can be waited on
   // will do something nontrivial.
@@ -391,7 +389,7 @@ MojoResult Dispatcher::AddAwakableImplNoLock(
 
 void Dispatcher::RemoveAwakableImplNoLock(Awakable* /*awakable*/,
                                           HandleSignalsState* signals_state) {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // By default, waiting isn't supported. Only dispatchers that can be waited on
   // will do something nontrivial.
@@ -421,7 +419,7 @@ bool Dispatcher::EndSerializeAndCloseImplNoLock(
 }
 
 bool Dispatcher::IsBusyNoLock() const {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
   // Most dispatchers support only "atomic" operations, so they are never busy
   // (in this sense).
@@ -429,7 +427,7 @@ bool Dispatcher::IsBusyNoLock() const {
 }
 
 void Dispatcher::CloseNoLock() {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
 
   is_closed_ = true;
@@ -439,7 +437,7 @@ void Dispatcher::CloseNoLock() {
 
 scoped_refptr<Dispatcher>
 Dispatcher::CreateEquivalentDispatcherAndCloseNoLock() {
-  mutex_.AssertHeld();
+  lock_.AssertAcquired();
   DCHECK(!is_closed_);
 
   is_closed_ = true;
@@ -477,7 +475,7 @@ bool Dispatcher::EndSerializeAndClose(
   // See the comment above |EndSerializeAndCloseImplNoLock()|. In brief: Locking
   // isn't actually needed, but we need to satisfy assertions (which we don't
   // want to remove or weaken).
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
 #endif
 
   return EndSerializeAndCloseImplNoLock(channel, destination, actual_size,
@@ -488,7 +486,7 @@ bool Dispatcher::EndSerializeAndClose(
 
 void DispatcherTransport::End() {
   DCHECK(dispatcher_);
-  dispatcher_->mutex_.Unlock();
+  dispatcher_->lock_.Release();
   dispatcher_ = nullptr;
 }
 
diff --git a/third_party/mojo/src/mojo/edk/system/dispatcher.h b/third_party/mojo/src/mojo/edk/system/dispatcher.h
index 98b39f4..ed6999d 100644
--- a/third_party/mojo/src/mojo/edk/system/dispatcher.h
+++ b/third_party/mojo/src/mojo/edk/system/dispatcher.h
@@ -13,10 +13,10 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
 #include "mojo/edk/embedder/platform_handle_vector.h"
 #include "mojo/edk/system/handle_signals_state.h"
 #include "mojo/edk/system/memory.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/c/system/buffer.h"
 #include "mojo/public/c/system/data_pipe.h"
@@ -54,9 +54,9 @@ DispatcherTryStartTransport(Dispatcher* dispatcher);
 
 // A |Dispatcher| implements Mojo primitives that are "attached" to a particular
 // handle. This includes most (all?) primitives except for |MojoWait...()|. This
-// object is thread-safe, with its state being protected by a single mutex
-// |mutex_|, which is also made available to implementation subclasses (via the
-// |mutex()| method).
+// object is thread-safe, with its state being protected by a single lock
+// |lock_|, which is also made available to implementation subclasses (via the
+// |lock()| method).
 class MOJO_SYSTEM_IMPL_EXPORT Dispatcher
     : public base::RefCountedThreadSafe<Dispatcher> {
  public:
@@ -73,9 +73,9 @@ class MOJO_SYSTEM_IMPL_EXPORT Dispatcher
   virtual Type GetType() const = 0;
 
   // These methods implement the various primitives named |Mojo...()|. These
-  // take |mutex_| and handle races with |Close()|. Then they call out to
-  // subclasses' |...ImplNoLock()| methods (still under |mutex_|), which
-  // actually implement the primitives.
+  // take |lock_| and handle races with |Close()|. Then they call out to
+  // subclasses' |...ImplNoLock()| methods (still under |lock_|), which actually
+  // implement the primitives.
   // NOTE(vtl): This puts a big lock around each dispatcher (i.e., handle), and
   // prevents the various |...ImplNoLock()|s from releasing the lock as soon as
   // possible. If this becomes an issue, we can rethink this.
@@ -221,100 +221,91 @@ class MOJO_SYSTEM_IMPL_EXPORT Dispatcher
   virtual ~Dispatcher();
 
   // These are to be overridden by subclasses (if necessary). They are called
-  // exactly once (first |CancelAllAwakablesNoLock()|, then |CloseImplNoLock()|)
-  // when the dispatcher is being closed.
-  virtual void CancelAllAwakablesNoLock() MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
-  virtual void CloseImplNoLock() MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
-
+  // exactly once -- first |CancelAllAwakablesNoLock()|, then
+  // |CloseImplNoLock()|,
+  // when the dispatcher is being closed. They are called under |lock_|.
+  virtual void CancelAllAwakablesNoLock();
+  virtual void CloseImplNoLock();
   virtual scoped_refptr<Dispatcher>
-  CreateEquivalentDispatcherAndCloseImplNoLock()
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_) = 0;
+  CreateEquivalentDispatcherAndCloseImplNoLock() = 0;
 
   // These are to be overridden by subclasses (if necessary). They are never
-  // called after the dispatcher has been closed. See the descriptions of the
-  // methods without the "ImplNoLock" for more information.
+  // called after the dispatcher has been closed. They are called under |lock_|.
+  // See the descriptions of the methods without the "ImplNoLock" for more
+  // information.
   virtual MojoResult WriteMessageImplNoLock(
       UserPointer<const void> bytes,
       uint32_t num_bytes,
       std::vector<DispatcherTransport>* transports,
-      MojoWriteMessageFlags flags) MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+      MojoWriteMessageFlags flags);
   virtual MojoResult ReadMessageImplNoLock(UserPointer<void> bytes,
                                            UserPointer<uint32_t> num_bytes,
                                            DispatcherVector* dispatchers,
                                            uint32_t* num_dispatchers,
-                                           MojoReadMessageFlags flags)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+                                           MojoReadMessageFlags flags);
   virtual MojoResult WriteDataImplNoLock(UserPointer<const void> elements,
                                          UserPointer<uint32_t> num_bytes,
-                                         MojoWriteDataFlags flags)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+                                         MojoWriteDataFlags flags);
   virtual MojoResult BeginWriteDataImplNoLock(
       UserPointer<void*> buffer,
       UserPointer<uint32_t> buffer_num_bytes,
-      MojoWriteDataFlags flags) MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
-  virtual MojoResult EndWriteDataImplNoLock(uint32_t num_bytes_written)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+      MojoWriteDataFlags flags);
+  virtual MojoResult EndWriteDataImplNoLock(uint32_t num_bytes_written);
   virtual MojoResult ReadDataImplNoLock(UserPointer<void> elements,
                                         UserPointer<uint32_t> num_bytes,
-                                        MojoReadDataFlags flags)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+                                        MojoReadDataFlags flags);
   virtual MojoResult BeginReadDataImplNoLock(
       UserPointer<const void*> buffer,
       UserPointer<uint32_t> buffer_num_bytes,
-      MojoReadDataFlags flags) MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
-  virtual MojoResult EndReadDataImplNoLock(uint32_t num_bytes_read)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+      MojoReadDataFlags flags);
+  virtual MojoResult EndReadDataImplNoLock(uint32_t num_bytes_read);
   virtual MojoResult DuplicateBufferHandleImplNoLock(
       UserPointer<const MojoDuplicateBufferHandleOptions> options,
-      scoped_refptr<Dispatcher>* new_dispatcher)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+      scoped_refptr<Dispatcher>* new_dispatcher);
   virtual MojoResult MapBufferImplNoLock(
       uint64_t offset,
       uint64_t num_bytes,
       MojoMapBufferFlags flags,
-      scoped_ptr<embedder::PlatformSharedBufferMapping>* mapping)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
-  virtual HandleSignalsState GetHandleSignalsStateImplNoLock() const
-      MOJO_SHARED_LOCKS_REQUIRED(mutex_);
+      scoped_ptr<embedder::PlatformSharedBufferMapping>* mapping);
+  virtual HandleSignalsState GetHandleSignalsStateImplNoLock() const;
   virtual MojoResult AddAwakableImplNoLock(Awakable* awakable,
                                            MojoHandleSignals signals,
                                            uint32_t context,
-                                           HandleSignalsState* signals_state)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+                                           HandleSignalsState* signals_state);
   virtual void RemoveAwakableImplNoLock(Awakable* awakable,
-                                        HandleSignalsState* signals_state)
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+                                        HandleSignalsState* signals_state);
 
   // These implement the API used to serialize dispatchers to a |Channel|
   // (described below). They will only be called on a dispatcher that's attached
   // to and "owned" by a |MessageInTransit|. See the non-"impl" versions for
   // more information.
   //
-  // Note: |StartSerializeImplNoLock()| is actually called with |mutex_| NOT
+  // Note: |StartSerializeImplNoLock()| is actually called with |lock_| NOT
   // held, since the dispatcher should only be accessible to the calling thread.
-  // On Debug builds, |EndSerializeAndCloseImplNoLock()| is called with |mutex_|
-  // held, to satisfy any |mutex_.AssertHeld()| (e.g., in |CloseImplNoLock()| --
-  // and anything it calls); disentangling those assertions is
+  // On Debug builds, |EndSerializeAndCloseImplNoLock()| is called with |lock_|
+  // held, to satisfy any |lock_.AssertAcquired()| (e.g., in |CloseImplNoLock()|
+  // -- and anything it calls); disentangling those assertions is
   // difficult/fragile, and would weaken our general checking of invariants.
   //
   // TODO(vtl): Consider making these pure virtual once most things support
   // being passed over a message pipe.
   virtual void StartSerializeImplNoLock(Channel* channel,
                                         size_t* max_size,
-                                        size_t* max_platform_handles)
-      MOJO_NOT_THREAD_SAFE;
+                                        size_t* max_platform_handles);
   virtual bool EndSerializeAndCloseImplNoLock(
       Channel* channel,
       void* destination,
       size_t* actual_size,
-      embedder::PlatformHandleVector* platform_handles) MOJO_NOT_THREAD_SAFE;
+      embedder::PlatformHandleVector* platform_handles);
 
   // This should be overridden to return true if/when there's an ongoing
   // operation (e.g., two-phase read/writes on data pipes) that should prevent a
   // handle from being sent over a message pipe (with status "busy").
-  virtual bool IsBusyNoLock() const MOJO_SHARED_LOCKS_REQUIRED(mutex_);
+  virtual bool IsBusyNoLock() const;
 
-  Mutex& mutex() const MOJO_LOCK_RETURNED(mutex_) { return mutex_; }
+  // Available to subclasses. (Note: Returns a non-const reference, just like
+  // |base::AutoLock|'s constructor takes a non-const reference.)
+  base::Lock& lock() const { return lock_; }
 
  private:
   friend class DispatcherTransport;
@@ -323,29 +314,20 @@ class MOJO_SYSTEM_IMPL_EXPORT Dispatcher
   // the dispatcher must not be closed already. (This is the "equivalent" of
   // |CreateEquivalentDispatcherAndCloseNoLock()|, for situations where the
   // dispatcher must be disposed of instead of "transferred".)
-  void CloseNoLock() MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  void CloseNoLock();
 
   // Creates an equivalent dispatcher -- representing the same resource as this
   // dispatcher -- and close (i.e., disable) this dispatcher. I.e., this
   // dispatcher will look as though it was closed, but the resource it
   // represents will be assigned to the new dispatcher. This must be called
   // under the dispatcher's lock.
-  scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndCloseNoLock()
-      MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex_);
+  scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndCloseNoLock();
 
   // API to serialize dispatchers to a |Channel|, exposed to only
   // |TransportData| (via |TransportData|). They may only be called on a
   // dispatcher attached to a |MessageInTransit| (and in particular not in
   // |CoreImpl|'s handle table).
   //
-  // TODO(vtl): The serialization API (and related implementation methods,
-  // including |DispatcherTransport|'s methods) is marked
-  // |MOJO_NOT_THREAD_SAFE|. This is because the threading requirements are
-  // somewhat complicated (e.g., |HandleTableAccess::TryStartTransport()| is
-  // really a try-lock function, amongst other things). We could/should do a
-  // more careful job annotating these methods.
-  // https://github.com/domokit/mojo/issues/322
-  //
   // Starts the serialization. Returns (via the two "out" parameters) the
   // maximum amount of space that may be needed to serialize this dispatcher to
   // the given |Channel| (no more than
@@ -358,7 +340,7 @@ class MOJO_SYSTEM_IMPL_EXPORT Dispatcher
   // dispatcher cannot be serialized to the given |Channel|).
   void StartSerialize(Channel* channel,
                       size_t* max_size,
-                      size_t* max_platform_handles) MOJO_NOT_THREAD_SAFE;
+                      size_t* max_platform_handles);
   // Completes the serialization of this dispatcher to the given |Channel| and
   // closes it. (This call will always follow an earlier call to
   // |StartSerialize()|, with the same |Channel|.) This does so by writing to
@@ -373,13 +355,12 @@ class MOJO_SYSTEM_IMPL_EXPORT Dispatcher
   bool EndSerializeAndClose(Channel* channel,
                             void* destination,
                             size_t* actual_size,
-                            embedder::PlatformHandleVector* platform_handles)
-      MOJO_NOT_THREAD_SAFE;
+                            embedder::PlatformHandleVector* platform_handles);
 
   // This protects the following members as well as any state added by
   // subclasses.
-  mutable Mutex mutex_;
-  bool is_closed_ MOJO_GUARDED_BY(mutex_);
+  mutable base::Lock lock_;
+  bool is_closed_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(Dispatcher);
 };
@@ -394,15 +375,12 @@ class MOJO_SYSTEM_IMPL_EXPORT DispatcherTransport {
  public:
   DispatcherTransport() : dispatcher_(nullptr) {}
 
-  void End() MOJO_NOT_THREAD_SAFE;
+  void End();
 
   Dispatcher::Type GetType() const { return dispatcher_->GetType(); }
-  bool IsBusy() const MOJO_NOT_THREAD_SAFE {
-    return dispatcher_->IsBusyNoLock();
-  }
-  void Close() MOJO_NOT_THREAD_SAFE { dispatcher_->CloseNoLock(); }
-  scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndClose()
-      MOJO_NOT_THREAD_SAFE {
+  bool IsBusy() const { return dispatcher_->IsBusyNoLock(); }
+  void Close() { dispatcher_->CloseNoLock(); }
+  scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndClose() {
     return dispatcher_->CreateEquivalentDispatcherAndCloseNoLock();
   }
 
diff --git a/third_party/mojo/src/mojo/edk/system/dispatcher_unittest.cc b/third_party/mojo/src/mojo/edk/system/dispatcher_unittest.cc
index c6431ff..10c2b86 100644
--- a/third_party/mojo/src/mojo/edk/system/dispatcher_unittest.cc
+++ b/third_party/mojo/src/mojo/edk/system/dispatcher_unittest.cc
@@ -31,7 +31,7 @@ class TrivialDispatcher final : public Dispatcher {
 
   scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock()
       override {
-    mutex().AssertHeld();
+    lock().AssertAcquired();
     return scoped_refptr<Dispatcher>(new TrivialDispatcher());
   }
 
diff --git a/third_party/mojo/src/mojo/edk/system/endpoint_relayer.cc b/third_party/mojo/src/mojo/edk/system/endpoint_relayer.cc
index 9655f9c..9630216 100644
--- a/third_party/mojo/src/mojo/edk/system/endpoint_relayer.cc
+++ b/third_party/mojo/src/mojo/edk/system/endpoint_relayer.cc
@@ -31,14 +31,14 @@ void EndpointRelayer::Init(ChannelEndpoint* endpoint0,
 }
 
 void EndpointRelayer::SetFilter(scoped_ptr<Filter> filter) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   filter_ = filter.Pass();
 }
 
 bool EndpointRelayer::OnReadMessage(unsigned port, MessageInTransit* message) {
   DCHECK(message);
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
 
   // If we're no longer the client, then reject the message.
   if (!endpoints_[port])
@@ -59,7 +59,7 @@ bool EndpointRelayer::OnReadMessage(unsigned port, MessageInTransit* message) {
 }
 
 void EndpointRelayer::OnDetachFromChannel(unsigned port) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
 
   if (endpoints_[port]) {
     endpoints_[port]->DetachFromClient();
diff --git a/third_party/mojo/src/mojo/edk/system/endpoint_relayer.h b/third_party/mojo/src/mojo/edk/system/endpoint_relayer.h
index cfeda24..8b17a50 100644
--- a/third_party/mojo/src/mojo/edk/system/endpoint_relayer.h
+++ b/third_party/mojo/src/mojo/edk/system/endpoint_relayer.h
@@ -7,8 +7,8 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
 #include "mojo/edk/system/channel_endpoint_client.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/cpp/system/macros.h"
 
@@ -68,8 +68,7 @@ class MOJO_SYSTEM_IMPL_EXPORT EndpointRelayer final
   static unsigned GetPeerPort(unsigned port);
 
   // Initialize this object. This must be called before any other method.
-  void Init(ChannelEndpoint* endpoint0,
-            ChannelEndpoint* endpoint1) MOJO_NOT_THREAD_SAFE;
+  void Init(ChannelEndpoint* endpoint0, ChannelEndpoint* endpoint1);
 
   // Sets (or resets) the filter, which can (optionally) handle/filter
   // |Type::ENDPOINT_CLIENT| messages (see |Filter| above).
@@ -82,9 +81,11 @@ class MOJO_SYSTEM_IMPL_EXPORT EndpointRelayer final
  private:
   ~EndpointRelayer() override;
 
-  Mutex mutex_;
-  scoped_refptr<ChannelEndpoint> endpoints_[2] MOJO_GUARDED_BY(mutex_);
-  scoped_ptr<Filter> filter_ MOJO_GUARDED_BY(mutex_);
+  // TODO(vtl): We could probably get away without the lock if we had a
+  // thread-safe |scoped_refptr|.
+  base::Lock lock_;  // Protects the following members.
+  scoped_refptr<ChannelEndpoint> endpoints_[2];
+  scoped_ptr<Filter> filter_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(EndpointRelayer);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/incoming_endpoint.cc b/third_party/mojo/src/mojo/edk/system/incoming_endpoint.cc
index eaa1825..cd091b1 100644
--- a/third_party/mojo/src/mojo/edk/system/incoming_endpoint.cc
+++ b/third_party/mojo/src/mojo/edk/system/incoming_endpoint.cc
@@ -23,7 +23,7 @@ scoped_refptr<ChannelEndpoint> IncomingEndpoint::Init() {
 }
 
 scoped_refptr<MessagePipe> IncomingEndpoint::ConvertToMessagePipe() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   scoped_refptr<MessagePipe> message_pipe(
       MessagePipe::CreateLocalProxyFromExisting(&message_queue_,
                                                 endpoint_.get()));
@@ -35,7 +35,7 @@ scoped_refptr<MessagePipe> IncomingEndpoint::ConvertToMessagePipe() {
 scoped_refptr<DataPipe> IncomingEndpoint::ConvertToDataPipeProducer(
     const MojoCreateDataPipeOptions& validated_options,
     size_t consumer_num_bytes) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   scoped_refptr<DataPipe> data_pipe(DataPipe::CreateRemoteConsumerFromExisting(
       validated_options, consumer_num_bytes, &message_queue_, endpoint_.get()));
   DCHECK(message_queue_.IsEmpty());
@@ -45,7 +45,7 @@ scoped_refptr<DataPipe> IncomingEndpoint::ConvertToDataPipeProducer(
 
 scoped_refptr<DataPipe> IncomingEndpoint::ConvertToDataPipeConsumer(
     const MojoCreateDataPipeOptions& validated_options) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   scoped_refptr<DataPipe> data_pipe(DataPipe::CreateRemoteProducerFromExisting(
       validated_options, &message_queue_, endpoint_.get()));
   DCHECK(message_queue_.IsEmpty());
@@ -54,7 +54,7 @@ scoped_refptr<DataPipe> IncomingEndpoint::ConvertToDataPipeConsumer(
 }
 
 void IncomingEndpoint::Close() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (endpoint_) {
     endpoint_->DetachFromClient();
     endpoint_ = nullptr;
@@ -63,7 +63,7 @@ void IncomingEndpoint::Close() {
 
 bool IncomingEndpoint::OnReadMessage(unsigned /*port*/,
                                      MessageInTransit* message) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (!endpoint_)
     return false;
 
diff --git a/third_party/mojo/src/mojo/edk/system/incoming_endpoint.h b/third_party/mojo/src/mojo/edk/system/incoming_endpoint.h
index bf0acf3..22bf0b9 100644
--- a/third_party/mojo/src/mojo/edk/system/incoming_endpoint.h
+++ b/third_party/mojo/src/mojo/edk/system/incoming_endpoint.h
@@ -8,9 +8,9 @@
 #include <stddef.h>
 
 #include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
 #include "mojo/edk/system/channel_endpoint_client.h"
 #include "mojo/edk/system/message_in_transit_queue.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/cpp/system/macros.h"
 
@@ -32,7 +32,7 @@ class MOJO_SYSTEM_IMPL_EXPORT IncomingEndpoint final
   IncomingEndpoint();
 
   // Must be called before any other method.
-  scoped_refptr<ChannelEndpoint> Init() MOJO_NOT_THREAD_SAFE;
+  scoped_refptr<ChannelEndpoint> Init();
 
   scoped_refptr<MessagePipe> ConvertToMessagePipe();
   scoped_refptr<DataPipe> ConvertToDataPipeProducer(
@@ -52,9 +52,9 @@ class MOJO_SYSTEM_IMPL_EXPORT IncomingEndpoint final
  private:
   ~IncomingEndpoint() override;
 
-  Mutex mutex_;
-  scoped_refptr<ChannelEndpoint> endpoint_ MOJO_GUARDED_BY(mutex_);
-  MessageInTransitQueue message_queue_ MOJO_GUARDED_BY(mutex_);
+  base::Lock lock_;  // Protects the following members.
+  scoped_refptr<ChannelEndpoint> endpoint_;
+  MessageInTransitQueue message_queue_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(IncomingEndpoint);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/ipc_support.cc b/third_party/mojo/src/mojo/edk/system/ipc_support.cc
index 7c4f3d4..424a130 100644
--- a/third_party/mojo/src/mojo/edk/system/ipc_support.cc
+++ b/third_party/mojo/src/mojo/edk/system/ipc_support.cc
@@ -141,9 +141,8 @@ embedder::ScopedPlatformHandle IPCSupport::ConnectToSlaveInternal(
 
   system::ProcessIdentifier peer_id = system::kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle platform_connection_handle;
-  CHECK_EQ(connection_manager()->Connect(connection_id, &peer_id,
-                                         &platform_connection_handle),
-           ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION);
+  CHECK(connection_manager()->Connect(connection_id, &peer_id,
+                                      &platform_connection_handle));
   DCHECK_EQ(peer_id, *slave_process_identifier);
   DCHECK(platform_connection_handle.is_valid());
   return platform_connection_handle;
@@ -155,9 +154,8 @@ embedder::ScopedPlatformHandle IPCSupport::ConnectToMasterInternal(
 
   system::ProcessIdentifier peer_id;
   embedder::ScopedPlatformHandle platform_connection_handle;
-  CHECK_EQ(connection_manager()->Connect(connection_id, &peer_id,
-                                         &platform_connection_handle),
-           ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION);
+  CHECK(connection_manager()->Connect(connection_id, &peer_id,
+                                      &platform_connection_handle));
   DCHECK_EQ(peer_id, system::kMasterProcessIdentifier);
   DCHECK(platform_connection_handle.is_valid());
   return platform_connection_handle;
diff --git a/third_party/mojo/src/mojo/edk/system/master_connection_manager.cc b/third_party/mojo/src/mojo/edk/system/master_connection_manager.cc
index 7e24a4a8..d756f73 100644
--- a/third_party/mojo/src/mojo/edk/system/master_connection_manager.cc
+++ b/third_party/mojo/src/mojo/edk/system/master_connection_manager.cc
@@ -21,8 +21,6 @@
 namespace mojo {
 namespace system {
 
-namespace {
-
 const ProcessIdentifier kFirstSlaveProcessIdentifier = 2;
 
 static_assert(kMasterProcessIdentifier != kInvalidProcessIdentifier,
@@ -32,29 +30,6 @@ static_assert(kFirstSlaveProcessIdentifier != kInvalidProcessIdentifier,
 static_assert(kMasterProcessIdentifier != kFirstSlaveProcessIdentifier,
               "Master and first slave process identifiers are the same");
 
-MessageInTransit::Subtype ConnectionManagerResultToMessageInTransitSubtype(
-    ConnectionManager::Result result) {
-  switch (result) {
-    case ConnectionManager::Result::FAILURE:
-      return MessageInTransit::Subtype::CONNECTION_MANAGER_ACK_FAILURE;
-    case ConnectionManager::Result::SUCCESS:
-      return MessageInTransit::Subtype::CONNECTION_MANAGER_ACK_SUCCESS;
-    case ConnectionManager::Result::SUCCESS_CONNECT_SAME_PROCESS:
-      return MessageInTransit::Subtype::
-          CONNECTION_MANAGER_ACK_SUCCESS_CONNECT_SAME_PROCESS;
-    case ConnectionManager::Result::SUCCESS_CONNECT_NEW_CONNECTION:
-      return MessageInTransit::Subtype::
-          CONNECTION_MANAGER_ACK_SUCCESS_CONNECT_NEW_CONNECTION;
-    case ConnectionManager::Result::SUCCESS_CONNECT_REUSE_CONNECTION:
-      return MessageInTransit::Subtype::
-          CONNECTION_MANAGER_ACK_SUCCESS_CONNECT_REUSE_CONNECTION;
-  }
-  NOTREACHED();
-  return MessageInTransit::Subtype::CONNECTION_MANAGER_ACK_FAILURE;
-}
-
-}  // namespace
-
 // MasterConnectionManager::Helper ---------------------------------------------
 
 // |MasterConnectionManager::Helper| is not thread-safe, and must only be used
@@ -140,38 +115,28 @@ void MasterConnectionManager::Helper::OnReadMessage(
 
   const ConnectionIdentifier* connection_id =
       reinterpret_cast<const ConnectionIdentifier*>(message_view.bytes());
-  Result result = Result::FAILURE;
+  bool result;
   ProcessIdentifier peer_process_identifier = kInvalidProcessIdentifier;
   embedder::ScopedPlatformHandle platform_handle;
   uint32_t num_bytes = 0;
   const void* bytes = nullptr;
   switch (message_view.subtype()) {
     case MessageInTransit::Subtype::CONNECTION_MANAGER_ALLOW_CONNECT:
-      result = owner_->AllowConnectImpl(process_identifier_, *connection_id)
-                   ? Result::SUCCESS
-                   : Result::FAILURE;
+      result = owner_->AllowConnectImpl(process_identifier_, *connection_id);
       break;
     case MessageInTransit::Subtype::CONNECTION_MANAGER_CANCEL_CONNECT:
-      result = owner_->CancelConnectImpl(process_identifier_, *connection_id)
-                   ? Result::SUCCESS
-                   : Result::FAILURE;
+      result = owner_->CancelConnectImpl(process_identifier_, *connection_id);
       break;
-    case MessageInTransit::Subtype::CONNECTION_MANAGER_CONNECT: {
+    case MessageInTransit::Subtype::CONNECTION_MANAGER_CONNECT:
       result = owner_->ConnectImpl(process_identifier_, *connection_id,
                                    &peer_process_identifier, &platform_handle);
-      DCHECK_NE(result, Result::SUCCESS);
-      // TODO(vtl): FIXME -- currently, nothing should generate
-      // SUCCESS_CONNECT_REUSE_CONNECTION.
-      CHECK_NE(result, Result::SUCCESS_CONNECT_REUSE_CONNECTION);
       // Success acks for "connect" have the peer process identifier as data
-      // (and also a platform handle in the case of "new connection" -- handled
-      // further below).
-      if (result != Result::FAILURE) {
+      // (and maybe also a platform handle).
+      if (result) {
         num_bytes = static_cast<uint32_t>(sizeof(peer_process_identifier));
         bytes = &peer_process_identifier;
       }
       break;
-    }
     default:
       LOG(ERROR) << "Invalid message subtype " << message_view.subtype();
       FatalError();  // WARNING: This destroys us.
@@ -180,21 +145,22 @@ void MasterConnectionManager::Helper::OnReadMessage(
 
   scoped_ptr<MessageInTransit> response(new MessageInTransit(
       MessageInTransit::Type::CONNECTION_MANAGER_ACK,
-      ConnectionManagerResultToMessageInTransitSubtype(result), num_bytes,
-      bytes));
+      result ? MessageInTransit::Subtype::CONNECTION_MANAGER_ACK_SUCCESS
+             : MessageInTransit::Subtype::CONNECTION_MANAGER_ACK_FAILURE,
+      num_bytes, bytes));
 
-  if (result == Result::SUCCESS_CONNECT_NEW_CONNECTION) {
+  if (platform_handle.is_valid()) {
+    // Only success acks for "connect" *may* have a platform handle attached.
+    DCHECK(result);
     DCHECK_EQ(message_view.subtype(),
               MessageInTransit::Subtype::CONNECTION_MANAGER_CONNECT);
-    DCHECK(platform_handle.is_valid());
+
     embedder::ScopedPlatformHandleVectorPtr platform_handles(
         new embedder::PlatformHandleVector());
     platform_handles->push_back(platform_handle.release());
     response->SetTransportData(make_scoped_ptr(
         new TransportData(platform_handles.Pass(),
                           raw_channel_->GetSerializedPlatformHandleSize())));
-  } else {
-    DCHECK(!platform_handle.is_valid());
   }
 
   if (!raw_channel_->WriteMessage(response.Pass())) {
@@ -295,7 +261,7 @@ ProcessIdentifier MasterConnectionManager::AddSlave(
 
   ProcessIdentifier slave_process_identifier;
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
     CHECK_NE(next_process_identifier_, kMasterProcessIdentifier);
     slave_process_identifier = next_process_identifier_;
     next_process_identifier_++;
@@ -322,7 +288,7 @@ ProcessIdentifier MasterConnectionManager::AddSlaveAndBootstrap(
   ProcessIdentifier slave_process_identifier =
       AddSlave(slave_info, platform_handle.Pass());
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   DCHECK(pending_connections_.find(connection_id) ==
          pending_connections_.end());
   PendingConnectionInfo* info =
@@ -362,10 +328,11 @@ bool MasterConnectionManager::CancelConnect(
   return CancelConnectImpl(kMasterProcessIdentifier, connection_id);
 }
 
-ConnectionManager::Result MasterConnectionManager::Connect(
+bool MasterConnectionManager::Connect(
     const ConnectionIdentifier& connection_id,
     ProcessIdentifier* peer_process_identifier,
     embedder::ScopedPlatformHandle* platform_handle) {
+  AssertNotOnPrivateThread();
   return ConnectImpl(kMasterProcessIdentifier, connection_id,
                      peer_process_identifier, platform_handle);
 }
@@ -375,7 +342,7 @@ bool MasterConnectionManager::AllowConnectImpl(
     const ConnectionIdentifier& connection_id) {
   DCHECK_NE(process_identifier, kInvalidProcessIdentifier);
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
 
   auto it = pending_connections_.find(connection_id);
   if (it == pending_connections_.end()) {
@@ -414,7 +381,7 @@ bool MasterConnectionManager::CancelConnectImpl(
     const ConnectionIdentifier& connection_id) {
   DCHECK_NE(process_identifier, kInvalidProcessIdentifier);
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
 
   auto it = pending_connections_.find(connection_id);
   if (it == pending_connections_.end()) {
@@ -441,7 +408,7 @@ bool MasterConnectionManager::CancelConnectImpl(
   return true;
 }
 
-ConnectionManager::Result MasterConnectionManager::ConnectImpl(
+bool MasterConnectionManager::ConnectImpl(
     ProcessIdentifier process_identifier,
     const ConnectionIdentifier& connection_id,
     ProcessIdentifier* peer_process_identifier,
@@ -451,7 +418,7 @@ ConnectionManager::Result MasterConnectionManager::ConnectImpl(
   DCHECK(platform_handle);
   DCHECK(!platform_handle->is_valid());  // Not technically wrong, but unlikely.
 
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
 
   auto it = pending_connections_.find(connection_id);
   if (it == pending_connections_.end()) {
@@ -459,7 +426,7 @@ ConnectionManager::Result MasterConnectionManager::ConnectImpl(
     LOG(ERROR) << "Connect() from process " << process_identifier
                << " for connection ID " << connection_id.ToString()
                << " which is not pending";
-    return Result::FAILURE;
+    return false;
   }
 
   PendingConnectionInfo* info = it->second;
@@ -476,27 +443,23 @@ ConnectionManager::Result MasterConnectionManager::ConnectImpl(
       LOG(ERROR) << "Connect() from process " << process_identifier
                  << " for connection ID " << connection_id.ToString()
                  << " which is neither connectee";
-      return Result::FAILURE;
+      return false;
     }
 
-    // TODO(vtl): FIXME -- add stuff for SUCCESS_CONNECT_REUSE_CONNECTION here.
-    Result result = Result::FAILURE;
     if (info->first == info->second) {
       platform_handle->reset();
       DCHECK(!info->remaining_handle.is_valid());
-      result = Result::SUCCESS_CONNECT_SAME_PROCESS;
     } else {
       embedder::PlatformChannelPair platform_channel_pair;
       *platform_handle = platform_channel_pair.PassServerHandle();
       DCHECK(platform_handle->is_valid());
       info->remaining_handle = platform_channel_pair.PassClientHandle();
       DCHECK(info->remaining_handle.is_valid());
-      result = Result::SUCCESS_CONNECT_NEW_CONNECTION;
     }
     DVLOG(1) << "Connection ID " << connection_id.ToString()
              << ": first Connect() from process identifier "
              << process_identifier;
-    return result;
+    return true;
   }
 
   ProcessIdentifier remaining_connectee;
@@ -516,7 +479,7 @@ ConnectionManager::Result MasterConnectionManager::ConnectImpl(
                << " in state " << info->state;
     pending_connections_.erase(it);
     delete info;
-    return Result::FAILURE;
+    return false;
   }
 
   if (process_identifier != remaining_connectee) {
@@ -525,28 +488,18 @@ ConnectionManager::Result MasterConnectionManager::ConnectImpl(
                << " which is not the remaining connectee";
     pending_connections_.erase(it);
     delete info;
-    return Result::FAILURE;
+    return false;
   }
 
   *peer_process_identifier = peer;
-
-  // TODO(vtl): FIXME -- add stuff for SUCCESS_CONNECT_REUSE_CONNECTION here.
-  Result result = Result::FAILURE;
-  if (info->first == info->second) {
-    platform_handle->reset();
-    DCHECK(!info->remaining_handle.is_valid());
-    result = Result::SUCCESS_CONNECT_SAME_PROCESS;
-  } else {
-    *platform_handle = info->remaining_handle.Pass();
-    DCHECK(platform_handle->is_valid());
-    result = Result::SUCCESS_CONNECT_NEW_CONNECTION;
-  }
+  *platform_handle = info->remaining_handle.Pass();
+  DCHECK((info->first == info->second) ^ platform_handle->is_valid());
   pending_connections_.erase(it);
   delete info;
   DVLOG(1) << "Connection ID " << connection_id.ToString()
            << ": second Connect() from process identifier "
            << process_identifier;
-  return result;
+  return true;
 }
 
 void MasterConnectionManager::ShutdownOnPrivateThread() {
@@ -602,7 +555,7 @@ void MasterConnectionManager::OnError(ProcessIdentifier process_identifier) {
   delete helper;
 
   {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
 
     // TODO(vtl): This isn't very efficient.
     for (auto it = pending_connections_.begin();
diff --git a/third_party/mojo/src/mojo/edk/system/master_connection_manager.h b/third_party/mojo/src/mojo/edk/system/master_connection_manager.h
index 497f449..b7992c8 100644
--- a/third_party/mojo/src/mojo/edk/system/master_connection_manager.h
+++ b/third_party/mojo/src/mojo/edk/system/master_connection_manager.h
@@ -9,10 +9,10 @@
 
 #include "base/containers/hash_tables.h"
 #include "base/memory/ref_counted.h"
+#include "base/synchronization/lock.h"
 #include "base/threading/thread.h"
 #include "mojo/edk/embedder/scoped_platform_handle.h"
 #include "mojo/edk/system/connection_manager.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/cpp/system/macros.h"
 
@@ -51,8 +51,7 @@ class MOJO_SYSTEM_IMPL_EXPORT MasterConnectionManager final
   // thread", on which |master_process_delegate|'s methods will be called. Both
   // must stay alive at least until after |Shutdown()| has been called.
   void Init(scoped_refptr<base::TaskRunner> delegate_thread_task_runner,
-            embedder::MasterProcessDelegate* master_process_delegate)
-      MOJO_NOT_THREAD_SAFE;
+            embedder::MasterProcessDelegate* master_process_delegate);
 
   // Adds a slave process and sets up/tracks a connection to that slave (using
   // |platform_handle|). |slave_info| is used by the caller/implementation of
@@ -76,12 +75,12 @@ class MOJO_SYSTEM_IMPL_EXPORT MasterConnectionManager final
       const ConnectionIdentifier& connection_id);
 
   // |ConnectionManager| methods:
-  void Shutdown() override MOJO_NOT_THREAD_SAFE;
+  void Shutdown() override;
   bool AllowConnect(const ConnectionIdentifier& connection_id) override;
   bool CancelConnect(const ConnectionIdentifier& connection_id) override;
-  Result Connect(const ConnectionIdentifier& connection_id,
-                 ProcessIdentifier* peer_process_identifier,
-                 embedder::ScopedPlatformHandle* platform_handle) override;
+  bool Connect(const ConnectionIdentifier& connection_id,
+               ProcessIdentifier* peer_process_identifier,
+               embedder::ScopedPlatformHandle* platform_handle) override;
 
  private:
   class Helper;
@@ -92,13 +91,13 @@ class MOJO_SYSTEM_IMPL_EXPORT MasterConnectionManager final
                         const ConnectionIdentifier& connection_id);
   bool CancelConnectImpl(ProcessIdentifier process_identifier,
                          const ConnectionIdentifier& connection_id);
-  Result ConnectImpl(ProcessIdentifier process_identifier,
-                     const ConnectionIdentifier& connection_id,
-                     ProcessIdentifier* peer_process_identifier,
-                     embedder::ScopedPlatformHandle* platform_handle);
+  bool ConnectImpl(ProcessIdentifier process_identifier,
+                   const ConnectionIdentifier& connection_id,
+                   ProcessIdentifier* peer_process_identifier,
+                   embedder::ScopedPlatformHandle* platform_handle);
 
   // These should only be called on |private_thread_|:
-  void ShutdownOnPrivateThread() MOJO_NOT_THREAD_SAFE;
+  void ShutdownOnPrivateThread();
   // Signals |*event| on completion.
   void AddSlaveOnPrivateThread(embedder::SlaveInfo slave_info,
                                embedder::ScopedPlatformHandle platform_handle,
@@ -133,15 +132,15 @@ class MOJO_SYSTEM_IMPL_EXPORT MasterConnectionManager final
   // The following members are only accessed on |private_thread_|:
   base::hash_map<ProcessIdentifier, Helper*> helpers_;  // Owns its values.
 
-  // Note: |mutex_| is not needed in the constructor, |Init()|,
-  // |Shutdown()|/|ShutdownOnPrivateThread()|, or the destructor
-  Mutex mutex_;
+  // Protects the members below (except in the constructor, |Init()|,
+  // |Shutdown()|/|ShutdownOnPrivateThread()|, and the destructor).
+  base::Lock lock_;
 
-  ProcessIdentifier next_process_identifier_ MOJO_GUARDED_BY(mutex_);
+  ProcessIdentifier next_process_identifier_;
 
   struct PendingConnectionInfo;
   base::hash_map<ConnectionIdentifier, PendingConnectionInfo*>
-      pending_connections_ MOJO_GUARDED_BY(mutex_);  // Owns its values.
+      pending_connections_;  // Owns its values.
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MasterConnectionManager);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/message_in_transit.h b/third_party/mojo/src/mojo/edk/system/message_in_transit.h
index c61cfd6..063c8d6 100644
--- a/third_party/mojo/src/mojo/edk/system/message_in_transit.h
+++ b/third_party/mojo/src/mojo/edk/system/message_in_transit.h
@@ -80,18 +80,11 @@ class MOJO_SYSTEM_IMPL_EXPORT MessageInTransit {
     CONNECTION_MANAGER_ALLOW_CONNECT = 0,
     CONNECTION_MANAGER_CANCEL_CONNECT = 1,
     CONNECTION_MANAGER_CONNECT = 2,
-    // Subtypes for type |Type::CONNECTION_MANAGER_ACK|, corresponding to
-    // |ConnectionManager::Result| values (failure and non-"connect" acks never
-    // have any message contents; success acks for "connect" always have a
-    // |ProcessIdentifier| as data and also a platform handle attached for "new
-    // connection"):
-    // TODO(vtl): FIXME -- probably, in the "connect, reuse connection" case,
-    // we'll have to send more information.
+    // Subtypes for type |Type::CONNECTION_MANAGER_ACK| (failure acks never have
+    // any message contents; success acks for "connect" always have a
+    // |ProcessIdentifier| as data and *may* have a platform handle attached):
     CONNECTION_MANAGER_ACK_FAILURE = 0,
     CONNECTION_MANAGER_ACK_SUCCESS = 1,
-    CONNECTION_MANAGER_ACK_SUCCESS_CONNECT_SAME_PROCESS = 2,
-    CONNECTION_MANAGER_ACK_SUCCESS_CONNECT_NEW_CONNECTION = 3,
-    CONNECTION_MANAGER_ACK_SUCCESS_CONNECT_REUSE_CONNECTION = 4,
   };
 
   // Messages (the header and data) must always be aligned to a multiple of this
diff --git a/third_party/mojo/src/mojo/edk/system/message_pipe_dispatcher.cc b/third_party/mojo/src/mojo/edk/system/message_pipe_dispatcher.cc
index c329e87..ddbe863 100644
--- a/third_party/mojo/src/mojo/edk/system/message_pipe_dispatcher.cc
+++ b/third_party/mojo/src/mojo/edk/system/message_pipe_dispatcher.cc
@@ -105,22 +105,22 @@ MessagePipeDispatcher::~MessagePipeDispatcher() {
 }
 
 MessagePipe* MessagePipeDispatcher::GetMessagePipeNoLock() const {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return message_pipe_.get();
 }
 
 unsigned MessagePipeDispatcher::GetPortNoLock() const {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return port_;
 }
 
 void MessagePipeDispatcher::CancelAllAwakablesNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   message_pipe_->CancelAllAwakables(port_);
 }
 
 void MessagePipeDispatcher::CloseImplNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   message_pipe_->Close(port_);
   message_pipe_ = nullptr;
   port_ = kInvalidPort;
@@ -128,7 +128,7 @@ void MessagePipeDispatcher::CloseImplNoLock() {
 
 scoped_refptr<Dispatcher>
 MessagePipeDispatcher::CreateEquivalentDispatcherAndCloseImplNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   // TODO(vtl): Currently, there are no options, so we just use
   // |kDefaultCreateOptions|. Eventually, we'll have to duplicate the options
@@ -149,7 +149,7 @@ MojoResult MessagePipeDispatcher::WriteMessageImplNoLock(
          (transports->size() > 0 &&
           transports->size() <= GetConfiguration().max_message_num_handles));
 
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   if (num_bytes > GetConfiguration().max_message_num_bytes)
     return MOJO_RESULT_RESOURCE_EXHAUSTED;
@@ -164,14 +164,14 @@ MojoResult MessagePipeDispatcher::ReadMessageImplNoLock(
     DispatcherVector* dispatchers,
     uint32_t* num_dispatchers,
     MojoReadMessageFlags flags) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return message_pipe_->ReadMessage(port_, bytes, num_bytes, dispatchers,
                                     num_dispatchers, flags);
 }
 
 HandleSignalsState MessagePipeDispatcher::GetHandleSignalsStateImplNoLock()
     const {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return message_pipe_->GetHandleSignalsState(port_);
 }
 
@@ -180,7 +180,7 @@ MojoResult MessagePipeDispatcher::AddAwakableImplNoLock(
     MojoHandleSignals signals,
     uint32_t context,
     HandleSignalsState* signals_state) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return message_pipe_->AddAwakable(port_, awakable, signals, context,
                                     signals_state);
 }
@@ -188,7 +188,7 @@ MojoResult MessagePipeDispatcher::AddAwakableImplNoLock(
 void MessagePipeDispatcher::RemoveAwakableImplNoLock(
     Awakable* awakable,
     HandleSignalsState* signals_state) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   message_pipe_->RemoveAwakable(port_, awakable, signals_state);
 }
 
diff --git a/third_party/mojo/src/mojo/edk/system/message_pipe_dispatcher.h b/third_party/mojo/src/mojo/edk/system/message_pipe_dispatcher.h
index 23bb1ed..9df5fed 100644
--- a/third_party/mojo/src/mojo/edk/system/message_pipe_dispatcher.h
+++ b/third_party/mojo/src/mojo/edk/system/message_pipe_dispatcher.h
@@ -42,8 +42,7 @@ class MOJO_SYSTEM_IMPL_EXPORT MessagePipeDispatcher final : public Dispatcher {
       MojoCreateMessagePipeOptions* out_options);
 
   // Must be called before any other methods. (This method is not thread-safe.)
-  void Init(scoped_refptr<MessagePipe> message_pipe,
-            unsigned port) MOJO_NOT_THREAD_SAFE;
+  void Init(scoped_refptr<MessagePipe> message_pipe, unsigned port);
 
   // |Dispatcher| public methods:
   Type GetType() const override;
@@ -100,18 +99,16 @@ class MOJO_SYSTEM_IMPL_EXPORT MessagePipeDispatcher final : public Dispatcher {
                                 HandleSignalsState* signals_state) override;
   void StartSerializeImplNoLock(Channel* channel,
                                 size_t* max_size,
-                                size_t* max_platform_handles) override
-      MOJO_NOT_THREAD_SAFE;
+                                size_t* max_platform_handles) override;
   bool EndSerializeAndCloseImplNoLock(
       Channel* channel,
       void* destination,
       size_t* actual_size,
-      embedder::PlatformHandleVector* platform_handles) override
-      MOJO_NOT_THREAD_SAFE;
+      embedder::PlatformHandleVector* platform_handles) override;
 
-  // This will be null if closed.
-  scoped_refptr<MessagePipe> message_pipe_ MOJO_GUARDED_BY(mutex());
-  unsigned port_ MOJO_GUARDED_BY(mutex());
+  // Protected by |lock()|:
+  scoped_refptr<MessagePipe> message_pipe_;  // This will be null if closed.
+  unsigned port_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MessagePipeDispatcher);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/mutex.cc b/third_party/mojo/src/mojo/edk/system/mutex.cc
deleted file mode 100644
index 216b35a..0000000
--- a/third_party/mojo/src/mojo/edk/system/mutex.cc
+++ /dev/null
@@ -1,38 +0,0 @@
-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "mojo/edk/system/mutex.h"
-
-#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
-
-#include "base/logging.h"
-
-namespace mojo {
-namespace system {
-
-Mutex::Mutex() : lock_() {
-}
-
-Mutex::~Mutex() {
-  DCHECK(owning_thread_ref_.is_null());
-}
-
-void Mutex::AssertHeld() const {
-  DCHECK(owning_thread_ref_ == base::PlatformThread::CurrentRef());
-}
-
-void Mutex::CheckHeldAndUnmark() {
-  DCHECK(owning_thread_ref_ == base::PlatformThread::CurrentRef());
-  owning_thread_ref_ = base::PlatformThreadRef();
-}
-
-void Mutex::CheckUnheldAndMark() {
-  DCHECK(owning_thread_ref_.is_null());
-  owning_thread_ref_ = base::PlatformThread::CurrentRef();
-}
-
-}  // namespace system
-}  // namespace mojo
-
-#endif  // !NDEBUG || DCHECK_ALWAYS_ON
diff --git a/third_party/mojo/src/mojo/edk/system/mutex.h b/third_party/mojo/src/mojo/edk/system/mutex.h
deleted file mode 100644
index acb410a..0000000
--- a/third_party/mojo/src/mojo/edk/system/mutex.h
+++ /dev/null
@@ -1,93 +0,0 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// A mutex class, with support for thread annotations.
-//
-// TODO(vtl): Currently, this is a fork of Chromium's
-// base/synchronization/lock.h (with names changed and minor modifications; it
-// still cheats and uses Chromium's lock_impl.*), but eventually we'll want our
-// own and, e.g., add support for non-exclusive (reader) locks.
-
-#ifndef MOJO_EDK_SYSTEM_MUTEX_H_
-#define MOJO_EDK_SYSTEM_MUTEX_H_
-
-#include "base/synchronization/lock_impl.h"
-#include "base/threading/platform_thread.h"
-#include "mojo/edk/system/system_impl_export.h"
-#include "mojo/edk/system/thread_annotations.h"
-#include "mojo/public/cpp/system/macros.h"
-
-namespace mojo {
-namespace system {
-
-// Mutex -----------------------------------------------------------------------
-
-class MOJO_SYSTEM_IMPL_EXPORT MOJO_LOCKABLE Mutex {
- public:
-#if defined(NDEBUG) && !defined(DCHECK_ALWAYS_ON)
-  Mutex() : lock_() {}
-  ~Mutex() {}
-
-  void Lock() MOJO_EXCLUSIVE_LOCK_FUNCTION() { lock_.Lock(); }
-  void Unlock() MOJO_UNLOCK_FUNCTION() { lock_.Unlock(); }
-
-  bool TryLock() MOJO_EXCLUSIVE_TRYLOCK_FUNCTION(true) { return lock_.Try(); }
-
-  void AssertHeld() const MOJO_ASSERT_EXCLUSIVE_LOCK() {}
-#else
-  Mutex();
-  ~Mutex();
-
-  void Lock() MOJO_EXCLUSIVE_LOCK_FUNCTION() {
-    lock_.Lock();
-    CheckUnheldAndMark();
-  }
-  void Unlock() MOJO_UNLOCK_FUNCTION() {
-    CheckHeldAndUnmark();
-    lock_.Unlock();
-  }
-
-  bool TryLock() MOJO_EXCLUSIVE_TRYLOCK_FUNCTION(true) {
-    bool rv = lock_.Try();
-    if (rv)
-      CheckUnheldAndMark();
-    return rv;
-  }
-
-  void AssertHeld() const MOJO_ASSERT_EXCLUSIVE_LOCK();
-#endif  // NDEBUG && !DCHECK_ALWAYS_ON
-
- private:
-#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
-  void CheckHeldAndUnmark();
-  void CheckUnheldAndMark();
-
-  base::PlatformThreadRef owning_thread_ref_;
-#endif  // !NDEBUG || DCHECK_ALWAYS_ON
-
-  base::internal::LockImpl lock_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(Mutex);
-};
-
-// MutexLocker -----------------------------------------------------------------
-
-class MOJO_SYSTEM_IMPL_EXPORT MOJO_SCOPED_LOCKABLE MutexLocker {
- public:
-  explicit MutexLocker(Mutex* mutex) MOJO_EXCLUSIVE_LOCK_FUNCTION(mutex)
-      : mutex_(mutex) {
-    this->mutex_->Lock();
-  }
-  ~MutexLocker() MOJO_UNLOCK_FUNCTION() { this->mutex_->Unlock(); }
-
- private:
-  Mutex* const mutex_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(MutexLocker);
-};
-
-}  // namespace system
-}  // namespace mojo
-
-#endif  // MOJO_EDK_SYSTEM_MUTEX_H_
diff --git a/third_party/mojo/src/mojo/edk/system/mutex_unittest.cc b/third_party/mojo/src/mojo/edk/system/mutex_unittest.cc
deleted file mode 100644
index 9b51653..0000000
--- a/third_party/mojo/src/mojo/edk/system/mutex_unittest.cc
+++ /dev/null
@@ -1,250 +0,0 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "mojo/edk/system/mutex.h"
-
-#include <stdlib.h>
-
-#include "base/threading/platform_thread.h"
-#include "mojo/edk/system/test_utils.h"
-#include "mojo/public/cpp/system/macros.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-namespace mojo {
-namespace system {
-namespace {
-
-// Sleeps for a "very small" amount of time.
-void EpsilonRandomSleep() {
-  test::Sleep(test::DeadlineFromMilliseconds(rand() % 20));
-}
-
-// Basic test to make sure that Lock()/Unlock()/TryLock() don't crash ----------
-
-class BasicMutexTestThread : public base::PlatformThread::Delegate {
- public:
-  explicit BasicMutexTestThread(Mutex* mutex) : mutex_(mutex), acquired_(0) {}
-
-  void ThreadMain() override {
-    for (int i = 0; i < 10; i++) {
-      mutex_->Lock();
-      mutex_->AssertHeld();
-      acquired_++;
-      mutex_->Unlock();
-    }
-    for (int i = 0; i < 10; i++) {
-      mutex_->Lock();
-      mutex_->AssertHeld();
-      acquired_++;
-      EpsilonRandomSleep();
-      mutex_->Unlock();
-    }
-    for (int i = 0; i < 10; i++) {
-      if (mutex_->TryLock()) {
-        mutex_->AssertHeld();
-        acquired_++;
-        EpsilonRandomSleep();
-        mutex_->Unlock();
-      }
-    }
-  }
-
-  int acquired() const { return acquired_; }
-
- private:
-  Mutex* mutex_;
-  int acquired_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(BasicMutexTestThread);
-};
-
-TEST(MutexTest, Basic) {
-  Mutex mutex;
-  BasicMutexTestThread thread(&mutex);
-  base::PlatformThreadHandle handle;
-
-  ASSERT_TRUE(base::PlatformThread::Create(0, &thread, &handle));
-
-  int acquired = 0;
-  for (int i = 0; i < 5; i++) {
-    mutex.Lock();
-    mutex.AssertHeld();
-    acquired++;
-    mutex.Unlock();
-  }
-  for (int i = 0; i < 10; i++) {
-    mutex.Lock();
-    mutex.AssertHeld();
-    acquired++;
-    EpsilonRandomSleep();
-    mutex.Unlock();
-  }
-  for (int i = 0; i < 10; i++) {
-    if (mutex.TryLock()) {
-      mutex.AssertHeld();
-      acquired++;
-      EpsilonRandomSleep();
-      mutex.Unlock();
-    }
-  }
-  for (int i = 0; i < 5; i++) {
-    mutex.Lock();
-    mutex.AssertHeld();
-    acquired++;
-    EpsilonRandomSleep();
-    mutex.Unlock();
-  }
-
-  base::PlatformThread::Join(handle);
-
-  EXPECT_GE(acquired, 20);
-  EXPECT_GE(thread.acquired(), 20);
-}
-
-// Test that TryLock() works as expected ---------------------------------------
-
-class TryLockTestThread : public base::PlatformThread::Delegate {
- public:
-  explicit TryLockTestThread(Mutex* mutex) : mutex_(mutex), got_lock_(false) {}
-
-  void ThreadMain() override MOJO_NO_THREAD_SAFETY_ANALYSIS {
-    got_lock_ = mutex_->TryLock();
-    if (got_lock_) {
-      mutex_->AssertHeld();
-      mutex_->Unlock();
-    }
-  }
-
-  bool got_lock() const { return got_lock_; }
-
- private:
-  Mutex* mutex_;
-  bool got_lock_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(TryLockTestThread);
-};
-
-TEST(MutexTest, TryLock) MOJO_NO_THREAD_SAFETY_ANALYSIS {
-  Mutex mutex;
-
-  ASSERT_TRUE(mutex.TryLock());
-  // We now have the mutex....
-
-  // This thread will not be able to get the mutex.
-  {
-    TryLockTestThread thread(&mutex);
-    base::PlatformThreadHandle handle;
-
-    ASSERT_TRUE(base::PlatformThread::Create(0, &thread, &handle));
-
-    base::PlatformThread::Join(handle);
-
-    ASSERT_FALSE(thread.got_lock());
-  }
-
-  mutex.Unlock();
-
-  // This thread will....
-  {
-    TryLockTestThread thread(&mutex);
-    base::PlatformThreadHandle handle;
-
-    ASSERT_TRUE(base::PlatformThread::Create(0, &thread, &handle));
-
-    base::PlatformThread::Join(handle);
-
-    ASSERT_TRUE(thread.got_lock());
-    // But it released it....
-    ASSERT_TRUE(mutex.TryLock());
-  }
-
-  mutex.Unlock();
-}
-
-// Tests that mutexes actually exclude -----------------------------------------
-
-class MutexLockTestThread : public base::PlatformThread::Delegate {
- public:
-  MutexLockTestThread(Mutex* mutex, int* value)
-      : mutex_(mutex), value_(value) {}
-
-  // Static helper which can also be called from the main thread.
-  static void DoStuff(Mutex* mutex, int* value) {
-    for (int i = 0; i < 40; i++) {
-      mutex->Lock();
-      int v = *value;
-      EpsilonRandomSleep();
-      *value = v + 1;
-      mutex->Unlock();
-    }
-  }
-
-  void ThreadMain() override { DoStuff(mutex_, value_); }
-
- private:
-  Mutex* mutex_;
-  int* value_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(MutexLockTestThread);
-};
-
-TEST(MutexTest, MutexTwoThreads) {
-  Mutex mutex;
-  int value = 0;
-
-  MutexLockTestThread thread(&mutex, &value);
-  base::PlatformThreadHandle handle;
-
-  ASSERT_TRUE(base::PlatformThread::Create(0, &thread, &handle));
-
-  MutexLockTestThread::DoStuff(&mutex, &value);
-
-  base::PlatformThread::Join(handle);
-
-  EXPECT_EQ(2 * 40, value);
-}
-
-TEST(MutexTest, MutexFourThreads) {
-  Mutex mutex;
-  int value = 0;
-
-  MutexLockTestThread thread1(&mutex, &value);
-  MutexLockTestThread thread2(&mutex, &value);
-  MutexLockTestThread thread3(&mutex, &value);
-  base::PlatformThreadHandle handle1;
-  base::PlatformThreadHandle handle2;
-  base::PlatformThreadHandle handle3;
-
-  ASSERT_TRUE(base::PlatformThread::Create(0, &thread1, &handle1));
-  ASSERT_TRUE(base::PlatformThread::Create(0, &thread2, &handle2));
-  ASSERT_TRUE(base::PlatformThread::Create(0, &thread3, &handle3));
-
-  MutexLockTestThread::DoStuff(&mutex, &value);
-
-  base::PlatformThread::Join(handle1);
-  base::PlatformThread::Join(handle2);
-  base::PlatformThread::Join(handle3);
-
-  EXPECT_EQ(4 * 40, value);
-}
-
-// MutexLocker -----------------------------------------------------------------
-
-TEST(MutexTest, MutexLocker) {
-  Mutex mutex;
-
-  {
-    MutexLocker locker(&mutex);
-    mutex.AssertHeld();
-  }
-
-  // The destruction of |locker| should unlock |mutex|.
-  ASSERT_TRUE(mutex.TryLock());
-  mutex.AssertHeld();
-  mutex.Unlock();
-}
-
-}  // namespace
-}  // namespace system
-}  // namespace mojo
diff --git a/third_party/mojo/src/mojo/edk/system/platform_handle_dispatcher.cc b/third_party/mojo/src/mojo/edk/system/platform_handle_dispatcher.cc
index 681b406..d33c960 100644
--- a/third_party/mojo/src/mojo/edk/system/platform_handle_dispatcher.cc
+++ b/third_party/mojo/src/mojo/edk/system/platform_handle_dispatcher.cc
@@ -22,7 +22,7 @@ struct SerializedPlatformHandleDispatcher {
 }  // namespace
 
 embedder::ScopedPlatformHandle PlatformHandleDispatcher::PassPlatformHandle() {
-  MutexLocker locker(&mutex());
+  base::AutoLock locker(lock());
   return platform_handle_.Pass();
 }
 
@@ -73,13 +73,13 @@ PlatformHandleDispatcher::~PlatformHandleDispatcher() {
 }
 
 void PlatformHandleDispatcher::CloseImplNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   platform_handle_.reset();
 }
 
 scoped_refptr<Dispatcher>
 PlatformHandleDispatcher::CreateEquivalentDispatcherAndCloseImplNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   return Create(platform_handle_.Pass());
 }
 
diff --git a/third_party/mojo/src/mojo/edk/system/platform_handle_dispatcher.h b/third_party/mojo/src/mojo/edk/system/platform_handle_dispatcher.h
index 8e8cf69..9e2e37d 100644
--- a/third_party/mojo/src/mojo/edk/system/platform_handle_dispatcher.h
+++ b/third_party/mojo/src/mojo/edk/system/platform_handle_dispatcher.h
@@ -48,16 +48,14 @@ class MOJO_SYSTEM_IMPL_EXPORT PlatformHandleDispatcher final
       override;
   void StartSerializeImplNoLock(Channel* channel,
                                 size_t* max_size,
-                                size_t* max_platform_handles) override
-      MOJO_NOT_THREAD_SAFE;
+                                size_t* max_platform_handles) override;
   bool EndSerializeAndCloseImplNoLock(
       Channel* channel,
       void* destination,
       size_t* actual_size,
-      embedder::PlatformHandleVector* platform_handles) override
-      MOJO_NOT_THREAD_SAFE;
+      embedder::PlatformHandleVector* platform_handles) override;
 
-  embedder::ScopedPlatformHandle platform_handle_ MOJO_GUARDED_BY(mutex());
+  embedder::ScopedPlatformHandle platform_handle_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(PlatformHandleDispatcher);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/raw_channel_unittest.cc b/third_party/mojo/src/mojo/edk/system/raw_channel_unittest.cc
index a901791..bc27889 100644
--- a/third_party/mojo/src/mojo/edk/system/raw_channel_unittest.cc
+++ b/third_party/mojo/src/mojo/edk/system/raw_channel_unittest.cc
@@ -19,6 +19,7 @@
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/scoped_vector.h"
 #include "base/rand_util.h"
+#include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/test/test_io_thread.h"
 #include "base/threading/simple_thread.h"
@@ -27,7 +28,6 @@
 #include "mojo/edk/embedder/platform_handle.h"
 #include "mojo/edk/embedder/scoped_platform_handle.h"
 #include "mojo/edk/system/message_in_transit.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/test_utils.h"
 #include "mojo/edk/system/transport_data.h"
 #include "mojo/edk/test/test_utils.h"
@@ -233,7 +233,7 @@ class ReadCheckerRawChannelDelegate : public RawChannel::Delegate {
     size_t expected_size;
     bool should_signal = false;
     {
-      MutexLocker locker(&mutex_);
+      base::AutoLock locker(lock_);
       CHECK_LT(position_, expected_sizes_.size());
       position = position_;
       expected_size = expected_sizes_[position];
@@ -261,7 +261,7 @@ class ReadCheckerRawChannelDelegate : public RawChannel::Delegate {
   void Wait() { done_event_.Wait(); }
 
   void SetExpectedSizes(const std::vector<uint32_t>& expected_sizes) {
-    MutexLocker locker(&mutex_);
+    base::AutoLock locker(lock_);
     CHECK_EQ(position_, expected_sizes_.size());
     expected_sizes_ = expected_sizes;
     position_ = 0;
@@ -270,9 +270,9 @@ class ReadCheckerRawChannelDelegate : public RawChannel::Delegate {
  private:
   base::WaitableEvent done_event_;
 
-  Mutex mutex_;
-  std::vector<uint32_t> expected_sizes_ MOJO_GUARDED_BY(mutex_);
-  size_t position_ MOJO_GUARDED_BY(mutex_);
+  base::Lock lock_;  // Protects the following members.
+  std::vector<uint32_t> expected_sizes_;
+  size_t position_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(ReadCheckerRawChannelDelegate);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/shared_buffer_dispatcher.cc b/third_party/mojo/src/mojo/edk/system/shared_buffer_dispatcher.cc
index caf8e0b..8ab8f10 100644
--- a/third_party/mojo/src/mojo/edk/system/shared_buffer_dispatcher.cc
+++ b/third_party/mojo/src/mojo/edk/system/shared_buffer_dispatcher.cc
@@ -177,14 +177,14 @@ MojoResult SharedBufferDispatcher::ValidateDuplicateOptions(
 }
 
 void SharedBufferDispatcher::CloseImplNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   DCHECK(shared_buffer_);
   shared_buffer_ = nullptr;
 }
 
 scoped_refptr<Dispatcher>
 SharedBufferDispatcher::CreateEquivalentDispatcherAndCloseImplNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   DCHECK(shared_buffer_);
   return CreateInternal(shared_buffer_.Pass());
 }
@@ -192,7 +192,7 @@ SharedBufferDispatcher::CreateEquivalentDispatcherAndCloseImplNoLock() {
 MojoResult SharedBufferDispatcher::DuplicateBufferHandleImplNoLock(
     UserPointer<const MojoDuplicateBufferHandleOptions> options,
     scoped_refptr<Dispatcher>* new_dispatcher) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   MojoDuplicateBufferHandleOptions validated_options;
   MojoResult result = ValidateDuplicateOptions(options, &validated_options);
@@ -209,7 +209,7 @@ MojoResult SharedBufferDispatcher::MapBufferImplNoLock(
     uint64_t num_bytes,
     MojoMapBufferFlags flags,
     scoped_ptr<embedder::PlatformSharedBufferMapping>* mapping) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   DCHECK(shared_buffer_);
 
   if (offset > static_cast<uint64_t>(std::numeric_limits<size_t>::max()))
diff --git a/third_party/mojo/src/mojo/edk/system/shared_buffer_dispatcher.h b/third_party/mojo/src/mojo/edk/system/shared_buffer_dispatcher.h
index 1222e03..deef5b4 100644
--- a/third_party/mojo/src/mojo/edk/system/shared_buffer_dispatcher.h
+++ b/third_party/mojo/src/mojo/edk/system/shared_buffer_dispatcher.h
@@ -93,17 +93,14 @@ class MOJO_SYSTEM_IMPL_EXPORT SharedBufferDispatcher final
       scoped_ptr<embedder::PlatformSharedBufferMapping>* mapping) override;
   void StartSerializeImplNoLock(Channel* channel,
                                 size_t* max_size,
-                                size_t* max_platform_handles) override
-      MOJO_NOT_THREAD_SAFE;
+                                size_t* max_platform_handles) override;
   bool EndSerializeAndCloseImplNoLock(
       Channel* channel,
       void* destination,
       size_t* actual_size,
-      embedder::PlatformHandleVector* platform_handles) override
-      MOJO_NOT_THREAD_SAFE;
+      embedder::PlatformHandleVector* platform_handles) override;
 
-  scoped_refptr<embedder::PlatformSharedBuffer> shared_buffer_
-      MOJO_GUARDED_BY(mutex());
+  scoped_refptr<embedder::PlatformSharedBuffer> shared_buffer_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(SharedBufferDispatcher);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/simple_dispatcher.cc b/third_party/mojo/src/mojo/edk/system/simple_dispatcher.cc
index 7264a12..f7db875 100644
--- a/third_party/mojo/src/mojo/edk/system/simple_dispatcher.cc
+++ b/third_party/mojo/src/mojo/edk/system/simple_dispatcher.cc
@@ -16,12 +16,12 @@ SimpleDispatcher::~SimpleDispatcher() {
 }
 
 void SimpleDispatcher::HandleSignalsStateChangedNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   awakable_list_.AwakeForStateChange(GetHandleSignalsStateImplNoLock());
 }
 
 void SimpleDispatcher::CancelAllAwakablesNoLock() {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   awakable_list_.CancelAll();
 }
 
@@ -30,7 +30,7 @@ MojoResult SimpleDispatcher::AddAwakableImplNoLock(
     MojoHandleSignals signals,
     uint32_t context,
     HandleSignalsState* signals_state) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
 
   HandleSignalsState state(GetHandleSignalsStateImplNoLock());
   if (state.satisfies(signals)) {
@@ -51,7 +51,7 @@ MojoResult SimpleDispatcher::AddAwakableImplNoLock(
 void SimpleDispatcher::RemoveAwakableImplNoLock(
     Awakable* awakable,
     HandleSignalsState* signals_state) {
-  mutex().AssertHeld();
+  lock().AssertAcquired();
   awakable_list_.Remove(awakable);
   if (signals_state)
     *signals_state = GetHandleSignalsStateImplNoLock();
diff --git a/third_party/mojo/src/mojo/edk/system/simple_dispatcher.h b/third_party/mojo/src/mojo/edk/system/simple_dispatcher.h
index a828435..1ec7ba7 100644
--- a/third_party/mojo/src/mojo/edk/system/simple_dispatcher.h
+++ b/third_party/mojo/src/mojo/edk/system/simple_dispatcher.h
@@ -25,8 +25,9 @@ class MOJO_SYSTEM_IMPL_EXPORT SimpleDispatcher : public Dispatcher {
   ~SimpleDispatcher() override;
 
   // To be called by subclasses when the state changes (so
-  // |GetHandleSignalsStateImplNoLock()| should be checked again).
-  void HandleSignalsStateChangedNoLock() MOJO_EXCLUSIVE_LOCKS_REQUIRED(mutex());
+  // |GetHandleSignalsStateImplNoLock()| should be checked again). Must be
+  // called under lock.
+  void HandleSignalsStateChangedNoLock();
 
   // |Dispatcher| protected methods:
   void CancelAllAwakablesNoLock() override;
@@ -38,7 +39,8 @@ class MOJO_SYSTEM_IMPL_EXPORT SimpleDispatcher : public Dispatcher {
                                 HandleSignalsState* signals_state) override;
 
  private:
-  AwakableList awakable_list_ MOJO_GUARDED_BY(mutex());
+  // Protected by |lock()|:
+  AwakableList awakable_list_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(SimpleDispatcher);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/simple_dispatcher_unittest.cc b/third_party/mojo/src/mojo/edk/system/simple_dispatcher_unittest.cc
index 051e108..c9a1510 100644
--- a/third_party/mojo/src/mojo/edk/system/simple_dispatcher_unittest.cc
+++ b/third_party/mojo/src/mojo/edk/system/simple_dispatcher_unittest.cc
@@ -28,11 +28,9 @@ class MockSimpleDispatcher final : public SimpleDispatcher {
   MockSimpleDispatcher()
       : state_(MOJO_HANDLE_SIGNAL_NONE,
                MOJO_HANDLE_SIGNAL_READABLE | MOJO_HANDLE_SIGNAL_WRITABLE) {}
-  explicit MockSimpleDispatcher(const HandleSignalsState& state)
-      : state_(state) {}
 
   void SetSatisfiedSignals(MojoHandleSignals new_satisfied_signals) {
-    MutexLocker locker(&mutex());
+    base::AutoLock locker(lock());
 
     // Any new signals that are set should be satisfiable.
     CHECK_EQ(new_satisfied_signals & ~state_.satisfied_signals,
@@ -47,7 +45,7 @@ class MockSimpleDispatcher final : public SimpleDispatcher {
   }
 
   void SetSatisfiableSignals(MojoHandleSignals new_satisfiable_signals) {
-    MutexLocker locker(&mutex());
+    base::AutoLock locker(lock());
 
     // Satisfied implies satisfiable.
     CHECK_EQ(new_satisfiable_signals & state_.satisfied_signals,
@@ -68,17 +66,19 @@ class MockSimpleDispatcher final : public SimpleDispatcher {
 
   scoped_refptr<Dispatcher> CreateEquivalentDispatcherAndCloseImplNoLock()
       override {
-    scoped_refptr<MockSimpleDispatcher> rv(new MockSimpleDispatcher(state_));
+    scoped_refptr<MockSimpleDispatcher> rv(new MockSimpleDispatcher());
+    rv->state_ = state_;
     return scoped_refptr<Dispatcher>(rv.get());
   }
 
   // |Dispatcher| override:
   HandleSignalsState GetHandleSignalsStateImplNoLock() const override {
-    mutex().AssertHeld();
+    lock().AssertAcquired();
     return state_;
   }
 
-  HandleSignalsState state_ MOJO_GUARDED_BY(mutex());
+  // Protected by |lock()|:
+  HandleSignalsState state_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MockSimpleDispatcher);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/slave_connection_manager.cc b/third_party/mojo/src/mojo/edk/system/slave_connection_manager.cc
index 7d0a998..d59bd82 100644
--- a/third_party/mojo/src/mojo/edk/system/slave_connection_manager.cc
+++ b/third_party/mojo/src/mojo/edk/system/slave_connection_manager.cc
@@ -22,9 +22,9 @@ SlaveConnectionManager::SlaveConnectionManager(
       slave_process_delegate_(),
       private_thread_("SlaveConnectionManagerPrivateThread"),
       awaiting_ack_type_(NOT_AWAITING_ACK),
-      ack_result_(nullptr),
-      ack_peer_process_identifier_(nullptr),
-      ack_platform_handle_(nullptr),
+      ack_result_(),
+      ack_peer_process_identifier_(),
+      ack_platform_handle_(),
       event_(false, false) {  // Auto-reset, not initially signalled.
 }
 
@@ -78,40 +78,38 @@ bool SlaveConnectionManager::AllowConnect(
     const ConnectionIdentifier& connection_id) {
   AssertNotOnPrivateThread();
 
-  MutexLocker locker(&mutex_);
-  Result result = Result::FAILURE;
+  base::AutoLock locker(lock_);
+  bool result = false;
   private_thread_.message_loop()->PostTask(
       FROM_HERE,
       base::Bind(&SlaveConnectionManager::AllowConnectOnPrivateThread,
                  base::Unretained(this), connection_id, &result));
   event_.Wait();
-  DCHECK(result == Result::FAILURE || result == Result::SUCCESS);
-  return result == Result::SUCCESS;
+  return result;
 }
 
 bool SlaveConnectionManager::CancelConnect(
     const ConnectionIdentifier& connection_id) {
   AssertNotOnPrivateThread();
 
-  MutexLocker locker(&mutex_);
-  Result result = Result::FAILURE;
+  base::AutoLock locker(lock_);
+  bool result = false;
   private_thread_.message_loop()->PostTask(
       FROM_HERE,
       base::Bind(&SlaveConnectionManager::CancelConnectOnPrivateThread,
                  base::Unretained(this), connection_id, &result));
   event_.Wait();
-  DCHECK(result == Result::FAILURE || result == Result::SUCCESS);
-  return result == Result::SUCCESS;
+  return result;
 }
 
-ConnectionManager::Result SlaveConnectionManager::Connect(
+bool SlaveConnectionManager::Connect(
     const ConnectionIdentifier& connection_id,
     ProcessIdentifier* peer_process_identifier,
     embedder::ScopedPlatformHandle* platform_handle) {
   AssertNotOnPrivateThread();
 
-  MutexLocker locker(&mutex_);
-  Result result = Result::FAILURE;
+  base::AutoLock locker(lock_);
+  bool result = false;
   private_thread_.message_loop()->PostTask(
       FROM_HERE, base::Bind(&SlaveConnectionManager::ConnectOnPrivateThread,
                             base::Unretained(this), connection_id, &result,
@@ -141,12 +139,12 @@ void SlaveConnectionManager::ShutdownOnPrivateThread() {
 
 void SlaveConnectionManager::AllowConnectOnPrivateThread(
     const ConnectionIdentifier& connection_id,
-    Result* result) {
+    bool* result) {
   DCHECK(result);
   AssertOnPrivateThread();
   // This should only posted (from another thread, to |private_thread_|) with
   // the lock held (until this thread triggers |event_|).
-  DCHECK(!mutex_.TryLock());
+  DCHECK(!lock_.Try());
   DCHECK_EQ(awaiting_ack_type_, NOT_AWAITING_ACK);
 
   DVLOG(1) << "Sending AllowConnect: connection ID "
@@ -156,7 +154,7 @@ void SlaveConnectionManager::AllowConnectOnPrivateThread(
           MessageInTransit::Subtype::CONNECTION_MANAGER_ALLOW_CONNECT,
           sizeof(connection_id), &connection_id)))) {
     // Don't tear things down; possibly we'll still read some messages.
-    *result = Result::FAILURE;
+    *result = false;
     event_.Signal();
     return;
   }
@@ -166,12 +164,12 @@ void SlaveConnectionManager::AllowConnectOnPrivateThread(
 
 void SlaveConnectionManager::CancelConnectOnPrivateThread(
     const ConnectionIdentifier& connection_id,
-    Result* result) {
+    bool* result) {
   DCHECK(result);
   AssertOnPrivateThread();
   // This should only posted (from another thread, to |private_thread_|) with
   // the lock held (until this thread triggers |event_|).
-  DCHECK(!mutex_.TryLock());
+  DCHECK(!lock_.Try());
   DCHECK_EQ(awaiting_ack_type_, NOT_AWAITING_ACK);
 
   DVLOG(1) << "Sending CancelConnect: connection ID "
@@ -181,7 +179,7 @@ void SlaveConnectionManager::CancelConnectOnPrivateThread(
           MessageInTransit::Subtype::CONNECTION_MANAGER_CANCEL_CONNECT,
           sizeof(connection_id), &connection_id)))) {
     // Don't tear things down; possibly we'll still read some messages.
-    *result = Result::FAILURE;
+    *result = false;
     event_.Signal();
     return;
   }
@@ -191,7 +189,7 @@ void SlaveConnectionManager::CancelConnectOnPrivateThread(
 
 void SlaveConnectionManager::ConnectOnPrivateThread(
     const ConnectionIdentifier& connection_id,
-    Result* result,
+    bool* result,
     ProcessIdentifier* peer_process_identifier,
     embedder::ScopedPlatformHandle* platform_handle) {
   DCHECK(result);
@@ -200,7 +198,7 @@ void SlaveConnectionManager::ConnectOnPrivateThread(
   AssertOnPrivateThread();
   // This should only posted (from another thread, to |private_thread_|) with
   // the lock held (until this thread triggers |event_|).
-  DCHECK(!mutex_.TryLock());
+  DCHECK(!lock_.Try());
   DCHECK_EQ(awaiting_ack_type_, NOT_AWAITING_ACK);
 
   DVLOG(1) << "Sending Connect: connection ID " << connection_id.ToString();
@@ -209,7 +207,7 @@ void SlaveConnectionManager::ConnectOnPrivateThread(
           MessageInTransit::Subtype::CONNECTION_MANAGER_CONNECT,
           sizeof(connection_id), &connection_id)))) {
     // Don't tear things down; possibly we'll still read some messages.
-    *result = Result::FAILURE;
+    *result = false;
     platform_handle->reset();
     event_.Signal();
     return;
@@ -225,8 +223,8 @@ void SlaveConnectionManager::OnReadMessage(
     embedder::ScopedPlatformHandleVectorPtr platform_handles) {
   AssertOnPrivateThread();
 
-  // Set |*ack_result_| to failure by default.
-  *ack_result_ = Result::FAILURE;
+  // Set |*ack_result_| to false by default.
+  *ack_result_ = false;
 
   // Note: Since we should be able to trust the master, simply crash (i.e.,
   // |CHECK()|-fail) if it sends us something invalid.
@@ -242,53 +240,38 @@ void SlaveConnectionManager::OnReadMessage(
   if (message_view.subtype() ==
       MessageInTransit::Subtype::CONNECTION_MANAGER_ACK_FAILURE) {
     // Failure acks never have any contents.
-    DCHECK_EQ(num_bytes, 0u);
-    DCHECK_EQ(num_platform_handles, 0u);
-    // Leave |*ack_result_| as failure.
-  } else {
-    if (awaiting_ack_type_ != AWAITING_CONNECT_ACK) {
-      // In the non-"connect" case, there's only one type of success ack, which
-      // never has any contents.
-      CHECK_EQ(message_view.subtype(),
-               MessageInTransit::Subtype::CONNECTION_MANAGER_ACK_SUCCESS);
-      DCHECK_EQ(num_bytes, 0u);
-      DCHECK_EQ(num_platform_handles, 0u);
-      *ack_result_ = Result::SUCCESS;
+    CHECK_EQ(num_bytes, 0u);
+    CHECK_EQ(num_platform_handles, 0u);
+    // Leave |*ack_result_| false.
+  } else if (message_view.subtype() ==
+             MessageInTransit::Subtype::CONNECTION_MANAGER_ACK_SUCCESS) {
+    if (awaiting_ack_type_ == AWAITING_ACCEPT_CONNECT_ACK ||
+        awaiting_ack_type_ == AWAITING_CANCEL_CONNECT_ACK) {
+      // Success acks for "accept/cancel connect" have no contents.
+      CHECK_EQ(num_bytes, 0u);
+      CHECK_EQ(num_platform_handles, 0u);
+      *ack_result_ = true;
       DCHECK(!ack_peer_process_identifier_);
       DCHECK(!ack_platform_handle_);
     } else {
-      // Success acks for "connect" always have a |ProcessIdentifier| as data.
+      DCHECK_EQ(awaiting_ack_type_, AWAITING_CONNECT_ACK);
+      // Success acks for "connect" always have a |ProcessIdentifier| as data,
+      // and *maybe* one platform handle.
       CHECK_EQ(num_bytes, sizeof(ProcessIdentifier));
+      CHECK_LE(num_platform_handles, 1u);
+      *ack_result_ = true;
       *ack_peer_process_identifier_ =
           *reinterpret_cast<const ProcessIdentifier*>(message_view.bytes());
-
-      switch (message_view.subtype()) {
-        case MessageInTransit::Subtype::
-            CONNECTION_MANAGER_ACK_SUCCESS_CONNECT_SAME_PROCESS:
-          DCHECK_EQ(num_platform_handles, 0u);
-          *ack_result_ = Result::SUCCESS_CONNECT_SAME_PROCESS;
-          ack_platform_handle_->reset();
-          break;
-        case MessageInTransit::Subtype::
-            CONNECTION_MANAGER_ACK_SUCCESS_CONNECT_NEW_CONNECTION:
-          CHECK_EQ(num_platform_handles, 1u);
-          *ack_result_ = Result::SUCCESS_CONNECT_NEW_CONNECTION;
-          ack_platform_handle_->reset(platform_handles->at(0));
-          platform_handles->at(0) = embedder::PlatformHandle();
-          break;
-        case MessageInTransit::Subtype::
-            CONNECTION_MANAGER_ACK_SUCCESS_CONNECT_REUSE_CONNECTION:
-          DCHECK_EQ(num_platform_handles, 0u);
-          *ack_result_ = Result::SUCCESS_CONNECT_REUSE_CONNECTION;
-          ack_platform_handle_->reset();
-          // TODO(vtl): FIXME -- currently, nothing should generate
-          // SUCCESS_CONNECT_REUSE_CONNECTION.
-          CHECK(false);
-          break;
-        default:
-          CHECK(false);
+      if (num_platform_handles > 0) {
+        ack_platform_handle_->reset(platform_handles->at(0));
+        platform_handles->at(0) = embedder::PlatformHandle();
+      } else {
+        ack_platform_handle_->reset();
       }
     }
+  } else {
+    // Bad message subtype.
+    CHECK(false);
   }
 
   awaiting_ack_type_ = NOT_AWAITING_ACK;
diff --git a/third_party/mojo/src/mojo/edk/system/slave_connection_manager.h b/third_party/mojo/src/mojo/edk/system/slave_connection_manager.h
index b2cd92c..40fc79b 100644
--- a/third_party/mojo/src/mojo/edk/system/slave_connection_manager.h
+++ b/third_party/mojo/src/mojo/edk/system/slave_connection_manager.h
@@ -7,12 +7,12 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
 #include "base/synchronization/waitable_event.h"
 #include "base/threading/thread.h"
 #include "mojo/edk/embedder/scoped_platform_handle.h"
 #include "mojo/edk/embedder/slave_process_delegate.h"
 #include "mojo/edk/system/connection_manager.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/raw_channel.h"
 #include "mojo/edk/system/system_impl_export.h"
 #include "mojo/public/cpp/system/macros.h"
@@ -58,20 +58,20 @@ class MOJO_SYSTEM_IMPL_EXPORT SlaveConnectionManager final
   void Shutdown() override;
   bool AllowConnect(const ConnectionIdentifier& connection_id) override;
   bool CancelConnect(const ConnectionIdentifier& connection_id) override;
-  Result Connect(const ConnectionIdentifier& connection_id,
-                 ProcessIdentifier* peer_process_identifier,
-                 embedder::ScopedPlatformHandle* platform_handle) override;
+  bool Connect(const ConnectionIdentifier& connection_id,
+               ProcessIdentifier* peer_process_identifier,
+               embedder::ScopedPlatformHandle* platform_handle) override;
 
  private:
   // These should only be called on |private_thread_|:
   void InitOnPrivateThread(embedder::ScopedPlatformHandle platform_handle);
   void ShutdownOnPrivateThread();
   void AllowConnectOnPrivateThread(const ConnectionIdentifier& connection_id,
-                                   Result* result);
+                                   bool* result);
   void CancelConnectOnPrivateThread(const ConnectionIdentifier& connection_id,
-                                    Result* result);
+                                    bool* result);
   void ConnectOnPrivateThread(const ConnectionIdentifier& connection_id,
-                              Result* result,
+                              bool* result,
                               ProcessIdentifier* peer_process_identifier,
                               embedder::ScopedPlatformHandle* platform_handle);
 
@@ -112,7 +112,7 @@ class MOJO_SYSTEM_IMPL_EXPORT SlaveConnectionManager final
     AWAITING_CONNECT_ACK
   };
   AwaitingAckType awaiting_ack_type_;
-  Result* ack_result_;
+  bool* ack_result_;
   // Used only when waiting for the ack to "connect":
   ProcessIdentifier* ack_peer_process_identifier_;
   embedder::ScopedPlatformHandle* ack_platform_handle_;
@@ -143,7 +143,7 @@ class MOJO_SYSTEM_IMPL_EXPORT SlaveConnectionManager final
   //
   // TODO(vtl): This is all a hack. It'd really suffice to have a version of
   // |RawChannel| with fully synchronous reading and writing.
-  Mutex mutex_;
+  base::Lock lock_;
   base::WaitableEvent event_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(SlaveConnectionManager);
diff --git a/third_party/mojo/src/mojo/edk/system/test_channel_endpoint_client.cc b/third_party/mojo/src/mojo/edk/system/test_channel_endpoint_client.cc
index b3e69b1..51d2a58 100644
--- a/third_party/mojo/src/mojo/edk/system/test_channel_endpoint_client.cc
+++ b/third_party/mojo/src/mojo/edk/system/test_channel_endpoint_client.cc
@@ -17,7 +17,7 @@ TestChannelEndpointClient::TestChannelEndpointClient()
 }
 
 void TestChannelEndpointClient::Init(unsigned port, ChannelEndpoint* endpoint) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   ASSERT_EQ(0u, port_);
   ASSERT_FALSE(endpoint_);
   port_ = port;
@@ -25,30 +25,30 @@ void TestChannelEndpointClient::Init(unsigned port, ChannelEndpoint* endpoint) {
 }
 
 bool TestChannelEndpointClient::IsDetached() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return !endpoint_;
 }
 
 size_t TestChannelEndpointClient::NumMessages() const {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   return messages_.Size();
 }
 
 scoped_ptr<MessageInTransit> TestChannelEndpointClient::PopMessage() {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   if (messages_.IsEmpty())
     return nullptr;
   return messages_.GetMessage();
 }
 
 void TestChannelEndpointClient::SetReadEvent(base::WaitableEvent* read_event) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
   read_event_ = read_event;
 }
 
 bool TestChannelEndpointClient::OnReadMessage(unsigned port,
                                               MessageInTransit* message) {
-  MutexLocker locker(&mutex_);
+  base::AutoLock locker(lock_);
 
   EXPECT_EQ(port_, port);
   EXPECT_TRUE(endpoint_);
@@ -61,9 +61,9 @@ bool TestChannelEndpointClient::OnReadMessage(unsigned port,
 }
 
 void TestChannelEndpointClient::OnDetachFromChannel(unsigned port) {
-  MutexLocker locker(&mutex_);
-
   EXPECT_EQ(port_, port);
+
+  base::AutoLock locker(lock_);
   ASSERT_TRUE(endpoint_);
   endpoint_->DetachFromClient();
   endpoint_ = nullptr;
diff --git a/third_party/mojo/src/mojo/edk/system/test_channel_endpoint_client.h b/third_party/mojo/src/mojo/edk/system/test_channel_endpoint_client.h
index bb812f0..c2347d5 100644
--- a/third_party/mojo/src/mojo/edk/system/test_channel_endpoint_client.h
+++ b/third_party/mojo/src/mojo/edk/system/test_channel_endpoint_client.h
@@ -7,10 +7,10 @@
 
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/synchronization/lock.h"
 #include "mojo/edk/system/channel_endpoint.h"
 #include "mojo/edk/system/channel_endpoint_client.h"
 #include "mojo/edk/system/message_in_transit_queue.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/public/cpp/system/macros.h"
 
 namespace base {
@@ -49,15 +49,15 @@ class TestChannelEndpointClient final : public ChannelEndpointClient {
  private:
   ~TestChannelEndpointClient() override;
 
-  mutable Mutex mutex_;
+  mutable base::Lock lock_;  // Protects the members below.
 
-  unsigned port_ MOJO_GUARDED_BY(mutex_);
-  scoped_refptr<ChannelEndpoint> endpoint_ MOJO_GUARDED_BY(mutex_);
+  unsigned port_;
+  scoped_refptr<ChannelEndpoint> endpoint_;
 
-  MessageInTransitQueue messages_ MOJO_GUARDED_BY(mutex_);
+  MessageInTransitQueue messages_;
 
   // Event to trigger if we read a message (may be null).
-  base::WaitableEvent* read_event_ MOJO_GUARDED_BY(mutex_);
+  base::WaitableEvent* read_event_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(TestChannelEndpointClient);
 };
diff --git a/third_party/mojo/src/mojo/edk/system/test_utils.h b/third_party/mojo/src/mojo/edk/system/test_utils.h
index 144e07b..6f8a96d 100644
--- a/third_party/mojo/src/mojo/edk/system/test_utils.h
+++ b/third_party/mojo/src/mojo/edk/system/test_utils.h
@@ -25,7 +25,7 @@ MojoDeadline EpsilonDeadline();
 // the order of 100 ms.)
 MojoDeadline TinyDeadline();
 
-// |TestTimeouts::action_timeout()|, as a |MojoDeadline|. (Expect this to be on
+// |TestTimeouts::action_timeout()|, as a |MojoDeadline|.(Expect this to be on
 // the order of 10 s.)
 MojoDeadline ActionDeadline();
 
diff --git a/third_party/mojo/src/mojo/edk/system/thread_annotations.h b/third_party/mojo/src/mojo/edk/system/thread_annotations.h
deleted file mode 100644
index ffac558..0000000
--- a/third_party/mojo/src/mojo/edk/system/thread_annotations.h
+++ /dev/null
@@ -1,85 +0,0 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// Macros for static thread-safety analysis.
-//
-// These are from http://clang.llvm.org/docs/ThreadSafetyAnalysis.html (and thus
-// really derive from google3's thread_annotations.h).
-//
-// TODO(vtl): We're still using the old-fashioned, deprecated annotations
-// ("locks" instead of "capabilities"), since the new ones don't work yet (in
-// particular, |TRY_ACQUIRE()| doesn't work: b/19264527).
-// https://github.com/domokit/mojo/issues/314
-
-#ifndef MOJO_EDK_SYSTEM_THREAD_ANNOTATIONS_H_
-#define MOJO_EDK_SYSTEM_THREAD_ANNOTATIONS_H_
-
-// Enable thread-safety attributes only with clang.
-// The attributes can be safely erased when compiling with other compilers.
-#if defined(__clang__)
-#define MOJO_THREAD_ANNOTATION_ATTRIBUTE__(x) __attribute__((x))
-#else
-#define MOJO_THREAD_ANNOTATION_ATTRIBUTE__(x)
-#endif
-
-#define MOJO_GUARDED_BY(x) MOJO_THREAD_ANNOTATION_ATTRIBUTE__(guarded_by(x))
-
-#define MOJO_PT_GUARDED_BY(x) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(pt_guarded_by(x))
-
-#define MOJO_ACQUIRED_AFTER(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(acquired_after(__VA_ARGS__))
-
-#define MOJO_ACQUIRED_BEFORE(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(acquired_before(__VA_ARGS__))
-
-#define MOJO_EXCLUSIVE_LOCKS_REQUIRED(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(exclusive_locks_required(__VA_ARGS__))
-
-#define MOJO_SHARED_LOCKS_REQUIRED(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(shared_locks_required(__VA_ARGS__))
-
-#define MOJO_LOCKS_EXCLUDED(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(locks_excluded(__VA_ARGS__))
-
-#define MOJO_LOCK_RETURNED(x) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(lock_returned(x))
-
-#define MOJO_LOCKABLE MOJO_THREAD_ANNOTATION_ATTRIBUTE__(lockable)
-
-#define MOJO_SCOPED_LOCKABLE MOJO_THREAD_ANNOTATION_ATTRIBUTE__(scoped_lockable)
-
-#define MOJO_EXCLUSIVE_LOCK_FUNCTION(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(exclusive_lock_function(__VA_ARGS__))
-
-#define MOJO_SHARED_LOCK_FUNCTION(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(shared_lock_function(__VA_ARGS__))
-
-#define MOJO_ASSERT_EXCLUSIVE_LOCK(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(assert_exclusive_lock(__VA_ARGS__))
-
-#define MOJO_ASSERT_SHARED_LOCK(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(assert_shared_lock(__VA_ARGS__))
-
-#define MOJO_EXCLUSIVE_TRYLOCK_FUNCTION(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(exclusive_trylock_function(__VA_ARGS__))
-
-#define MOJO_SHARED_TRYLOCK_FUNCTION(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(shared_trylock_function(__VA_ARGS__))
-
-#define MOJO_UNLOCK_FUNCTION(...) \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(unlock_function(__VA_ARGS__))
-
-#define MOJO_NO_THREAD_SAFETY_ANALYSIS \
-  MOJO_THREAD_ANNOTATION_ATTRIBUTE__(no_thread_safety_analysis)
-
-// Use this in the header to annotate a function/method as not being
-// thread-safe. This is equivalent to |MOJO_NO_THREAD_SAFETY_ANALYSIS|, but
-// semantically different: it declares that the caller must abide by additional
-// restrictions. Limitation: Unfortunately, you can't apply this to a method in
-// an interface (i.e., pure virtual method) and have it applied automatically to
-// implementations.
-#define MOJO_NOT_THREAD_SAFE MOJO_NO_THREAD_SAFETY_ANALYSIS
-
-#endif  // MOJO_EDK_SYSTEM_THREAD_ANNOTATIONS_H_
diff --git a/third_party/mojo/src/mojo/edk/system/thread_annotations_unittest.cc b/third_party/mojo/src/mojo/edk/system/thread_annotations_unittest.cc
deleted file mode 100644
index d56814f..0000000
--- a/third_party/mojo/src/mojo/edk/system/thread_annotations_unittest.cc
+++ /dev/null
@@ -1,124 +0,0 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-// Tests of the static thread annotation macros. These fall into two categories,
-// positive tests (testing that correct code compiles and works) and negative
-// tests (testing that incorrect code does not compile).
-//
-// Unfortunately, we don't have systematic/automated negative compilation tests.
-// So instead we have some cheesy macros that you can define to enable
-// individual compilation failures.
-
-#include "mojo/edk/system/thread_annotations.h"
-
-#include "mojo/edk/system/mutex.h"
-#include "mojo/public/cpp/system/macros.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-// Uncomment these to enable particular compilation failure tests.
-// #define NC_GUARDED_BY
-// TODO(vtl): |ACQUIRED_{BEFORE,AFTER}()| are currently unimplemented in clang
-// as of 2015-07-06 ("To be fixed in a future update."). So this actually
-// compiles!
-// #define NC_ACQUIRED_BEFORE
-
-namespace mojo {
-namespace system {
-namespace {
-
-// Test MOJO_GUARDED_BY --------------------------------------------------------
-
-class GuardedByClass {
- public:
-  GuardedByClass() : x_() {}
-  ~GuardedByClass() {}
-
-  void GoodSet(int x) {
-    mu_.Lock();
-    x_ = x;
-    mu_.Unlock();
-  }
-
-#ifdef NC_GUARDED_BY
-  void BadSet(int x) { x_ = x; }
-#endif
-
- private:
-  Mutex mu_;
-  int x_ MOJO_GUARDED_BY(mu_);
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(GuardedByClass);
-};
-
-TEST(ThreadAnnotationsTest, GuardedBy) {
-  GuardedByClass c;
-  c.GoodSet(123);
-}
-
-// Test MOJO_ACQUIRED_BEFORE ---------------------------------------------------
-
-class AcquiredBeforeClass2;
-
-class AcquiredBeforeClass1 {
- public:
-  AcquiredBeforeClass1() {}
-  ~AcquiredBeforeClass1() {}
-
-  void NoOp() {
-    mu_.Lock();
-    mu_.Unlock();
-  }
-
-#ifdef NC_ACQUIRED_BEFORE
-  void BadMethod(AcquiredBeforeClass2* c2) {
-    mu_.Lock();
-    c2->NoOp();
-    mu_.Unlock();
-  }
-#endif
-
- private:
-  friend class AcquiredBeforeClass2;
-
-  Mutex mu_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(AcquiredBeforeClass1);
-};
-
-class AcquiredBeforeClass2 {
- public:
-  AcquiredBeforeClass2() {}
-  ~AcquiredBeforeClass2() {}
-
-  void NoOp() {
-    mu_.Lock();
-    mu_.Unlock();
-  }
-
-  void GoodMethod(AcquiredBeforeClass1* c1) {
-    mu_.Lock();
-    c1->NoOp();
-    mu_.Unlock();
-  }
-
- private:
-  Mutex mu_ MOJO_ACQUIRED_BEFORE(AcquiredBeforeClass1::mu_);
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(AcquiredBeforeClass2);
-};
-
-TEST(ThreadAnnotationsTest, AcquiredBefore) {
-  AcquiredBeforeClass1 c1;
-  AcquiredBeforeClass2 c2;
-  c2.GoodMethod(&c1);
-#ifdef NC_ACQUIRED_BEFORE
-  c1.BadMethod(&c2);
-#endif
-}
-
-// TODO(vtl): Test more things.
-
-}  // namespace
-}  // namespace system
-}  // namespace mojo
diff --git a/third_party/mojo/src/mojo/edk/system/waiter_unittest.cc b/third_party/mojo/src/mojo/edk/system/waiter_unittest.cc
index 29bd5bc..68f8106 100644
--- a/third_party/mojo/src/mojo/edk/system/waiter_unittest.cc
+++ b/third_party/mojo/src/mojo/edk/system/waiter_unittest.cc
@@ -11,8 +11,8 @@
 
 #include <stdint.h>
 
+#include "base/synchronization/lock.h"
 #include "base/threading/simple_thread.h"
-#include "mojo/edk/system/mutex.h"
 #include "mojo/edk/system/test_utils.h"
 #include "mojo/public/cpp/system/macros.h"
 #include "testing/gtest/include/gtest/gtest.h"
@@ -41,7 +41,7 @@ class WaitingThread : public base::SimpleThread {
                      MojoDeadline* elapsed) {
     for (;;) {
       {
-        MutexLocker locker(&mutex_);
+        base::AutoLock locker(lock_);
         if (done_) {
           *result = result_;
           *context = context_;
@@ -68,7 +68,7 @@ class WaitingThread : public base::SimpleThread {
     elapsed = stopwatch.Elapsed();
 
     {
-      MutexLocker locker(&mutex_);
+      base::AutoLock locker(lock_);
       done_ = true;
       result_ = result;
       context_ = context;
@@ -79,11 +79,11 @@ class WaitingThread : public base::SimpleThread {
   const MojoDeadline deadline_;
   Waiter waiter_;  // Thread-safe.
 
-  Mutex mutex_;
-  bool done_ MOJO_GUARDED_BY(mutex_);
-  MojoResult result_ MOJO_GUARDED_BY(mutex_);
-  uint32_t context_ MOJO_GUARDED_BY(mutex_);
-  MojoDeadline elapsed_ MOJO_GUARDED_BY(mutex_);
+  base::Lock lock_;  // Protects the following members.
+  bool done_;
+  MojoResult result_;
+  uint32_t context_;
+  MojoDeadline elapsed_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(WaitingThread);
 };
diff --git a/third_party/mojo/src/mojo/edk/test/BUILD.gn b/third_party/mojo/src/mojo/edk/test/BUILD.gn
index 834d837..fa6f836 100644
--- a/third_party/mojo/src/mojo/edk/test/BUILD.gn
+++ b/third_party/mojo/src/mojo/edk/test/BUILD.gn
@@ -89,7 +89,6 @@ mojo_edk_source_set("test_support_impl") {
 group("public_tests") {
   testonly = true
   deps = [
-    ":mojo_public_bindings_perftests",
     ":mojo_public_bindings_unittests",
     ":mojo_public_environment_unittests",
     ":mojo_public_system_perftests",
@@ -119,13 +118,6 @@ test("mojo_public_bindings_unittests") {
   ]
 }
 
-test("mojo_public_bindings_perftests") {
-  deps = [
-    ":run_all_perftests",
-    "../../public/cpp/bindings/tests:perftests",
-  ]
-}
-
 test("mojo_public_environment_unittests") {
   deps = [
     ":run_all_unittests",
diff --git a/third_party/mojo/src/mojo/public/VERSION b/third_party/mojo/src/mojo/public/VERSION
index cb44eda..0841b63 100644
--- a/third_party/mojo/src/mojo/public/VERSION
+++ b/third_party/mojo/src/mojo/public/VERSION
@@ -1 +1 @@
-c02a28868825edfa57ab77947b8cb15e741c5598
\ No newline at end of file
+a05bfef8096006056b2fff78092faf14d1319782
\ No newline at end of file
diff --git a/third_party/mojo/src/mojo/public/c/gpu/DEPS b/third_party/mojo/src/mojo/public/c/gpu/DEPS
deleted file mode 100644
index 9be0bc0..0000000
--- a/third_party/mojo/src/mojo/public/c/gpu/DEPS
+++ /dev/null
@@ -1,3 +0,0 @@
-include_rules = [
-  "+gpu",
-]
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/BUILD.gn b/third_party/mojo/src/mojo/public/cpp/bindings/BUILD.gn
index e345313..05e92be 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/BUILD.gn
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/BUILD.gn
@@ -8,6 +8,7 @@ mojo_sdk_source_set("bindings") {
   sources = [
     "array.h",
     "binding.h",
+    "error_handler.h",
     "interface_ptr.h",
     "interface_ptr_info.h",
     "interface_request.h",
@@ -41,6 +42,8 @@ mojo_sdk_source_set("bindings") {
     "lib/message_header_validator.cc",
     "lib/message_header_validator.h",
     "lib/message_internal.h",
+    "lib/message_queue.cc",
+    "lib/message_queue.h",
     "lib/no_interface.cc",
     "lib/router.cc",
     "lib/router.h",
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/binding.h b/third_party/mojo/src/mojo/public/cpp/bindings/binding.h
index 250945a..4609521 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/binding.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/binding.h
@@ -7,6 +7,7 @@
 
 #include "mojo/public/c/environment/async_waiter.h"
 #include "mojo/public/cpp/bindings/callback.h"
+#include "mojo/public/cpp/bindings/error_handler.h"
 #include "mojo/public/cpp/bindings/interface_ptr.h"
 #include "mojo/public/cpp/bindings/interface_ptr_info.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
@@ -101,8 +102,9 @@ class Binding {
   // Tears down the binding, closing the message pipe and leaving the interface
   // implementation unbound.
   ~Binding() {
-    if (internal_router_)
+    if (internal_router_) {
       Close();
+    }
   }
 
   // Completes a binding that was constructed with only an interface
@@ -185,6 +187,19 @@ class Binding {
     connection_error_handler_ = error_handler;
   }
 
+  // Similar to the method above but uses the ErrorHandler interface instead of
+  // a callback.
+  // NOTE: Deprecated. Please use the method above.
+  // TODO(yzshen): Remove this method once all callsites are converted.
+  void set_error_handler(ErrorHandler* error_handler) {
+    if (error_handler) {
+      set_connection_error_handler(
+          [error_handler]() { error_handler->OnConnectionError(); });
+    } else {
+      set_connection_error_handler(Closure());
+    }
+  }
+
   // Returns the interface implementation that was previously specified. Caller
   // does not take ownership.
   Interface* impl() { return impl_; }
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/callback.h b/third_party/mojo/src/mojo/public/cpp/bindings/callback.h
index beec1a1..17d1caf 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/callback.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/callback.h
@@ -37,7 +37,7 @@ class Callback<void(Args...)> {
   explicit Callback(Runnable* runnable) : sink_(runnable) {}
 
   // As above, but can take an object that isn't derived from Runnable, so long
-  // as it has a compatible operator() or Run() method. operator() will be
+  // as it has a compatible operator() or Run() method.  operator() will be
   // preferred if the type has both.
   template <typename Sink>
   Callback(const Sink& sink) {
@@ -47,11 +47,6 @@ class Callback<void(Args...)> {
     sink_ = internal::SharedPtr<Runnable>(new sink_type(sink));
   }
 
-  // As above, but can take a compatible function pointer.
-  Callback(void (*function_ptr)(
-      typename internal::Callback_ParamTraits<Args>::ForwardType...))
-      : sink_(new FunctionPtrAdapter(function_ptr)) {}
-
   // Executes the callback function, invoking Pass() on move-only types.
   void Run(typename internal::Callback_ParamTraits<Args>::ForwardType... args)
       const {
@@ -78,7 +73,7 @@ class Callback<void(Args...)> {
     Sink sink;
   };
 
-  // Adapts a class that has a compatible operator() to be callable by Callback.
+  // Adapts a class that has a compatible operator() callable by Callback.
   template <typename Sink>
   struct FunctorAdapter : public Runnable {
     explicit FunctorAdapter(const Sink& sink) : sink(sink) {}
@@ -90,20 +85,6 @@ class Callback<void(Args...)> {
     Sink sink;
   };
 
-  // Adapts a function pointer.
-  struct FunctionPtrAdapter : public Runnable {
-    explicit FunctionPtrAdapter(void (*function_ptr)(
-        typename internal::Callback_ParamTraits<Args>::ForwardType...))
-        : function_ptr(function_ptr) {}
-    virtual void Run(
-        typename internal::Callback_ParamTraits<Args>::ForwardType... args)
-        const override {
-      (*function_ptr)(internal::Forward(args)...);
-    }
-    void (*function_ptr)(
-        typename internal::Callback_ParamTraits<Args>::ForwardType...);
-  };
-
   internal::SharedPtr<Runnable> sink_;
 };
 
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/error_handler.h b/third_party/mojo/src/mojo/public/cpp/bindings/error_handler.h
new file mode 100644
index 0000000..8ce1af2
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/error_handler.h
@@ -0,0 +1,19 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_PUBLIC_CPP_BINDINGS_ERROR_HANDLER_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_ERROR_HANDLER_H_
+
+namespace mojo {
+
+// This interface is used to report connection errors.
+class ErrorHandler {
+ public:
+  virtual ~ErrorHandler() {}
+  virtual void OnConnectionError() = 0;
+};
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_ERROR_HANDLER_H_
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/interface_impl.h b/third_party/mojo/src/mojo/public/cpp/bindings/interface_impl.h
new file mode 100644
index 0000000..c65f6e3
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/interface_impl.h
@@ -0,0 +1,178 @@
+// Copyright 2014 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_IMPL_H_
+#define MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_IMPL_H_
+
+#include "mojo/public/cpp/bindings/binding.h"
+#include "mojo/public/cpp/bindings/interface_ptr_info.h"
+#include "mojo/public/cpp/bindings/interface_request.h"
+#include "mojo/public/cpp/environment/environment.h"
+#include "mojo/public/cpp/system/macros.h"
+
+namespace mojo {
+
+// DEPRECATED! Please use mojo::Binding instead of InterfaceImpl<> in new code.
+//
+// InterfaceImpl<..> is designed to be the base class of an interface
+// implementation. It may be bound to a pipe or a proxy, see BindToPipe and
+// BindToProxy.
+template <typename Interface>
+class InterfaceImpl : public Interface, public ErrorHandler {
+ public:
+  using ImplementedInterface = Interface;
+
+  InterfaceImpl() : binding_(this), error_handler_impl_(this) {
+    binding_.set_error_handler(&error_handler_impl_);
+  }
+  virtual ~InterfaceImpl() {}
+
+  void BindToHandle(
+      ScopedMessagePipeHandle handle,
+      const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter()) {
+    binding_.Bind(handle.Pass(), waiter);
+  }
+
+  bool WaitForIncomingMethodCall() {
+    return binding_.WaitForIncomingMethodCall();
+  }
+
+  internal::Router* internal_router() { return binding_.internal_router(); }
+
+  // Implements ErrorHandler.
+  //
+  // Called when the underlying pipe is closed. After this point no more
+  // calls will be made on Interface and all responses will be silently ignored.
+  void OnConnectionError() override {}
+
+  void set_delete_on_error(bool delete_on_error) {
+    error_handler_impl_.set_delete_on_error(delete_on_error);
+  }
+
+ private:
+  class ErrorHandlerImpl : public ErrorHandler {
+   public:
+    explicit ErrorHandlerImpl(InterfaceImpl* impl) : impl_(impl) {}
+    ~ErrorHandlerImpl() override {}
+
+    // ErrorHandler implementation:
+    void OnConnectionError() override {
+      // If the the instance is not bound to the pipe, the instance might choose
+      // to delete the binding in the OnConnectionError handler, which would in
+      // turn delete |this|.  Save the error behavior before invoking the error
+      // handler so we can correctly decide what to do.
+      bool delete_on_error = delete_on_error_;
+      impl_->OnConnectionError();
+      if (delete_on_error)
+        delete impl_;
+    }
+
+    void set_delete_on_error(bool delete_on_error) {
+      delete_on_error_ = delete_on_error;
+    }
+
+   private:
+    InterfaceImpl* impl_;
+    bool delete_on_error_ = false;
+
+    MOJO_DISALLOW_COPY_AND_ASSIGN(ErrorHandlerImpl);
+  };
+
+  Binding<Interface> binding_;
+  ErrorHandlerImpl error_handler_impl_;
+
+  MOJO_DISALLOW_COPY_AND_ASSIGN(InterfaceImpl);
+};
+
+// Takes an instance of an InterfaceImpl<..> subclass and binds it to the given
+// MessagePipe. The instance is returned for convenience in member initializer
+// lists, etc.
+//
+// If the pipe is closed, the instance's OnConnectionError method will be called
+// and then the instance will be deleted.
+//
+// The instance is also bound to the current thread. Its methods will only be
+// called on the current thread, and if the current thread exits, then the end
+// point of the pipe will be closed and the error handler's OnConnectionError
+// method will be called.
+template <typename Impl>
+Impl* BindToPipe(
+    Impl* instance,
+    ScopedMessagePipeHandle handle,
+    const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter()) {
+  instance->set_delete_on_error(true);
+  instance->BindToHandle(handle.Pass(), waiter);
+  return instance;
+}
+
+// Like BindToPipe but does not delete the instance after a channel error.
+template <typename Impl>
+Impl* WeakBindToPipe(
+    Impl* instance,
+    ScopedMessagePipeHandle handle,
+    const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter()) {
+  instance->BindToHandle(handle.Pass(), waiter);
+  return instance;
+}
+
+// Takes an instance of an InterfaceImpl<..> subclass and binds it to the given
+// InterfacePtr<..>. The instance is returned for convenience in member
+// initializer lists, etc. If the pipe is closed, the instance's
+// OnConnectionError method will be called and then the instance will be
+// deleted.
+//
+// The instance is also bound to the current thread. Its methods will only be
+// called on the current thread, and if the current thread exits, then it will
+// also be deleted, and along with it, its end point of the pipe will be closed.
+template <typename Impl, typename Interface>
+Impl* BindToProxy(
+    Impl* instance,
+    InterfacePtr<Interface>* ptr,
+    const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter()) {
+  instance->set_delete_on_error(true);
+  WeakBindToProxy(instance, ptr, waiter);
+  return instance;
+}
+
+// Like BindToProxy but does not delete the instance after a channel error.
+template <typename Impl, typename Interface>
+Impl* WeakBindToProxy(
+    Impl* instance,
+    InterfacePtr<Interface>* ptr,
+    const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter()) {
+  MessagePipe pipe;
+  ptr->Bind(InterfacePtrInfo<Interface>(pipe.handle0.Pass(), 0u), waiter);
+  instance->BindToHandle(pipe.handle1.Pass(), waiter);
+  return instance;
+}
+
+// Takes an instance of an InterfaceImpl<..> subclass and binds it to the given
+// InterfaceRequest<..>. The instance is returned for convenience in member
+// initializer lists, etc. If the pipe is closed, the instance's
+// OnConnectionError method will be called and then the instance will be
+// deleted.
+//
+// The instance is also bound to the current thread. Its methods will only be
+// called on the current thread, and if the current thread exits, then it will
+// also be deleted, and along with it, its end point of the pipe will be closed.
+template <typename Impl, typename Interface>
+Impl* BindToRequest(
+    Impl* instance,
+    InterfaceRequest<Interface>* request,
+    const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter()) {
+  return BindToPipe(instance, request->PassMessagePipe(), waiter);
+}
+
+// Like BindToRequest but does not delete the instance after a channel error.
+template <typename Impl, typename Interface>
+Impl* WeakBindToRequest(
+    Impl* instance,
+    InterfaceRequest<Interface>* request,
+    const MojoAsyncWaiter* waiter = Environment::GetDefaultAsyncWaiter()) {
+  return WeakBindToPipe(instance, request->PassMessagePipe(), waiter);
+}
+
+}  // namespace mojo
+
+#endif  // MOJO_PUBLIC_CPP_BINDINGS_INTERFACE_IMPL_H_
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/interface_ptr.h b/third_party/mojo/src/mojo/public/cpp/bindings/interface_ptr.h
index 00514dd..04f4902 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/interface_ptr.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/interface_ptr.h
@@ -8,6 +8,7 @@
 #include <algorithm>
 
 #include "mojo/public/cpp/bindings/callback.h"
+#include "mojo/public/cpp/bindings/error_handler.h"
 #include "mojo/public/cpp/bindings/interface_ptr_info.h"
 #include "mojo/public/cpp/bindings/lib/interface_ptr_internal.h"
 #include "mojo/public/cpp/environment/environment.h"
@@ -73,9 +74,6 @@ class InterfacePtr {
       internal_state_.Bind(info.Pass(), waiter);
   }
 
-  // Returns whether or not this InterfacePtr is bound to a message pipe.
-  bool is_bound() const { return internal_state_.is_bound(); }
-
   // Returns a raw pointer to the local proxy. Caller does not take ownership.
   // Note that the local proxy is thread hostile, as stated above.
   Interface* get() const { return internal_state_.instance(); }
@@ -136,6 +134,19 @@ class InterfacePtr {
     internal_state_.set_connection_error_handler(error_handler);
   }
 
+  // Similar to the method above but uses the ErrorHandler interface instead of
+  // a callback.
+  // NOTE: Deprecated. Please use the method above.
+  // TODO(yzshen): Remove this method once all callsites are converted.
+  void set_error_handler(ErrorHandler* error_handler) {
+    if (error_handler) {
+      set_connection_error_handler(
+          [error_handler]() { error_handler->OnConnectionError(); });
+    } else {
+      set_connection_error_handler(Closure());
+    }
+  }
+
   // Unbinds the InterfacePtr and returns the information which could be used
   // to setup an InterfacePtr again. This method may be used to move the proxy
   // to a different thread (see class comments for details).
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/connector.cc b/third_party/mojo/src/mojo/public/cpp/bindings/lib/connector.cc
index 597bf8d..24d993d1 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/connector.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/connector.cc
@@ -4,6 +4,7 @@
 
 #include "mojo/public/cpp/bindings/lib/connector.h"
 
+#include "mojo/public/cpp/bindings/error_handler.h"
 #include "mojo/public/cpp/environment/logging.h"
 
 namespace mojo {
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/connector.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/connector.h
index f36761c..a6c0d1b 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/connector.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/connector.h
@@ -7,6 +7,7 @@
 
 #include "mojo/public/c/environment/async_waiter.h"
 #include "mojo/public/cpp/bindings/callback.h"
+#include "mojo/public/cpp/bindings/lib/message_queue.h"
 #include "mojo/public/cpp/bindings/message.h"
 #include "mojo/public/cpp/environment/environment.h"
 #include "mojo/public/cpp/system/core.h"
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/map_data_internal.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/map_data_internal.h
index 6d629b4..8315dbc 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/map_data_internal.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/map_data_internal.h
@@ -13,25 +13,22 @@
 namespace mojo {
 namespace internal {
 
-namespace {
-const ArrayValidateParams* GetMapKeyValidateParamsDefault() {
-  // The memory allocated here never gets released because calling a
-  // destructor at exit time makes clang unhappy.
+inline const ArrayValidateParams* GetMapKeyValidateParamsDefault() {
+  // The memory allocated here never gets released to not cause an exit time
+  // destructor.
   static const ArrayValidateParams* validate_params =
       new ArrayValidateParams(0, false, nullptr);
   return validate_params;
 }
 
-const ArrayValidateParams* GetMapKeyValidateParamsForStrings() {
-  // The memory allocated here never gets released because calling a
-  // destructor at exit time makes clang unhappy.
+inline const ArrayValidateParams* GetMapKeyValidateParamsForStrings() {
+  // The memory allocated here never gets released to not cause an exit time
+  // destructor.
   static const ArrayValidateParams* validate_params = new ArrayValidateParams(
       0, false, new ArrayValidateParams(0, false, nullptr));
   return validate_params;
 }
 
-}  // namespace
-
 template <typename MapKey>
 struct MapKeyValidateParamsFactory {
   static const ArrayValidateParams* Get() {
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/message_queue.cc b/third_party/mojo/src/mojo/public/cpp/bindings/lib/message_queue.cc
index 65b9a5c..fd701e97 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/message_queue.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/message_queue.cc
@@ -2,13 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "mojo/public/cpp/bindings/tests/message_queue.h"
+#include "mojo/public/cpp/bindings/lib/message_queue.h"
 
 #include "mojo/public/cpp/bindings/message.h"
 #include "mojo/public/cpp/environment/logging.h"
 
 namespace mojo {
-namespace test {
+namespace internal {
 
 MessageQueue::MessageQueue() {
 }
@@ -22,6 +22,11 @@ bool MessageQueue::IsEmpty() const {
   return queue_.empty();
 }
 
+Message* MessageQueue::Peek() {
+  MOJO_DCHECK(!queue_.empty());
+  return queue_.front();
+}
+
 void MessageQueue::Push(Message* message) {
   queue_.push(new Message());
   queue_.back()->Swap(message);
@@ -39,5 +44,5 @@ void MessageQueue::Pop() {
   queue_.pop();
 }
 
-}  // namespace test
+}  // namespace internal
 }  // namespace mojo
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/message_queue.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/message_queue.h
index c47ca99..4e46b54 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/message_queue.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/message_queue.h
@@ -12,7 +12,7 @@
 namespace mojo {
 class Message;
 
-namespace test {
+namespace internal {
 
 // A queue for Message objects.
 class MessageQueue {
@@ -21,23 +21,27 @@ class MessageQueue {
   ~MessageQueue();
 
   bool IsEmpty() const;
+  Message* Peek();
 
-  // This method copies the message data and steals ownership of its handles.
+  // This method transfers ownership of |message->data| and |message->handles|
+  // to the message queue, resetting |message| in the process.
   void Push(Message* message);
 
-  // Removes the next message from the queue, copying its data and transferring
-  // ownership of its handles to the given |message|.
+  // Removes the next message from the queue, transferring ownership of its
+  // data and handles to the given |message|.
   void Pop(Message* message);
 
- private:
+  // Removes the next message from the queue, discarding its data and handles.
+  // This is meant to be used in conjunction with |Peek|.
   void Pop();
 
+ private:
   std::queue<Message*> queue_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(MessageQueue);
 };
 
-}  // namespace test
+}  // namespace internal
 }  // namespace mojo
 
 #endif  // MOJO_PUBLIC_CPP_BINDINGS_LIB_MESSAGE_QUEUE_H_
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/strong_binding.h b/third_party/mojo/src/mojo/public/cpp/bindings/strong_binding.h
index 860260e..48c74c6 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/strong_binding.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/strong_binding.h
@@ -10,6 +10,7 @@
 #include "mojo/public/c/environment/async_waiter.h"
 #include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/bindings/callback.h"
+#include "mojo/public/cpp/bindings/error_handler.h"
 #include "mojo/public/cpp/bindings/interface_ptr.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/cpp/bindings/lib/filter_chain.h"
@@ -103,11 +104,21 @@ class StrongBinding {
     return binding_.WaitForIncomingMethodCall();
   }
 
-  // Note: The error handler must not delete the interface implementation.
   void set_connection_error_handler(const Closure& error_handler) {
     connection_error_handler_ = error_handler;
   }
 
+  // NOTE: Deprecated. Please use the method above.
+  // TODO(yzshen): Remove this method once all callsites are converted.
+  void set_error_handler(ErrorHandler* error_handler) {
+    if (error_handler) {
+      set_connection_error_handler(
+          [error_handler]() { error_handler->OnConnectionError(); });
+    } else {
+      set_connection_error_handler(Closure());
+    }
+  }
+
   Interface* impl() { return binding_.impl(); }
   // Exposed for testing, should not generally be used.
   internal::Router* internal_router() { return binding_.internal_router(); }
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/BUILD.gn b/third_party/mojo/src/mojo/public/cpp/bindings/tests/BUILD.gn
index d087cbf..bb94bc2 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/BUILD.gn
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/BUILD.gn
@@ -23,8 +23,6 @@ mojo_sdk_source_set("tests") {
     "handle_passing_unittest.cc",
     "interface_ptr_unittest.cc",
     "map_unittest.cc",
-    "message_queue.cc",
-    "message_queue.h",
     "request_response_unittest.cc",
     "router_unittest.cc",
     "sample_service_unittest.cc",
@@ -53,28 +51,6 @@ mojo_sdk_source_set("tests") {
   ]
 }
 
-mojo_sdk_source_set("perftests") {
-  testonly = true
-
-  sources = [
-    "bindings_perftest.cc",
-  ]
-
-  deps = [
-    "//testing/gtest",
-  ]
-
-  mojo_sdk_deps = [
-    "mojo/public/cpp/bindings",
-    "mojo/public/cpp/bindings:callback",
-    "mojo/public/cpp/environment:standalone",
-    "mojo/public/cpp/system",
-    "mojo/public/cpp/test_support:test_utils",
-    "mojo/public/cpp/utility",
-    "mojo/public/interfaces/bindings/tests:test_interfaces",
-  ]
-}
-
 mojo_sdk_source_set("mojo_public_bindings_test_utils") {
   sources = [
     "validation_test_input_parser.cc",
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/binding_callback_unittest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/binding_callback_unittest.cc
index 3bc018c..8ec51bf 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/binding_callback_unittest.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/binding_callback_unittest.cc
@@ -3,7 +3,6 @@
 // found in the LICENSE file.
 
 #include "build/build_config.h"
-#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/bindings/interface_ptr.h"
 #include "mojo/public/cpp/bindings/string.h"
 #include "mojo/public/cpp/environment/environment.h"
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/binding_unittest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/binding_unittest.cc
index 59d2501..ef23279 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/binding_unittest.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/binding_unittest.cc
@@ -2,13 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-// Note: This file tests both binding.h (mojo::Binding) and strong_binding.h
-// (mojo::StrongBinding).
-
 #include "mojo/public/cpp/bindings/binding.h"
-#include "mojo/public/cpp/bindings/strong_binding.h"
 #include "mojo/public/cpp/environment/environment.h"
-#include "mojo/public/cpp/system/macros.h"
 #include "mojo/public/cpp/utility/run_loop.h"
 #include "mojo/public/interfaces/bindings/tests/sample_interfaces.mojom.h"
 #include "mojo/public/interfaces/bindings/tests/sample_service.mojom.h"
@@ -17,28 +12,10 @@
 namespace mojo {
 namespace {
 
-class BindingTestBase : public testing::Test {
- public:
-  BindingTestBase() {}
-  ~BindingTestBase() override {}
-
-  RunLoop& loop() { return loop_; }
-
- private:
-  Environment env_;
-  RunLoop loop_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(BindingTestBase);
-};
-
 class ServiceImpl : public sample::Service {
  public:
-  explicit ServiceImpl(bool* was_deleted = nullptr)
-      : was_deleted_(was_deleted) {}
-  ~ServiceImpl() override {
-    if (was_deleted_)
-      *was_deleted_ = true;
-  }
+  ServiceImpl() {}
+  ~ServiceImpl() override {}
 
  private:
   // sample::Service implementation
@@ -49,29 +26,30 @@ class ServiceImpl : public sample::Service {
     callback.Run(1);
   }
   void GetPort(InterfaceRequest<sample::Port> port) override {}
-
-  bool* const was_deleted_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(ServiceImpl);
 };
 
-// BindingTest -----------------------------------------------------------------
+class IntegerAccessorImpl : public sample::IntegerAccessor {
+ public:
+  IntegerAccessorImpl() {}
+  ~IntegerAccessorImpl() override {}
 
-using BindingTest = BindingTestBase;
+ private:
+  // sample::IntegerAccessor implementation.
+  void GetInteger(const GetIntegerCallback& callback) override {
+    callback.Run(1, sample::ENUM_VALUE);
+  }
+  void SetInteger(int64_t data, sample::Enum type) override {}
+};
 
-TEST_F(BindingTest, Close) {
-  bool called = false;
-  sample::ServicePtr ptr;
-  auto request = GetProxy(&ptr);
-  ptr.set_connection_error_handler([&called]() { called = true; });
-  ServiceImpl impl;
-  Binding<sample::Service> binding(&impl, request.Pass());
+class BindingTest : public testing::Test {
+ public:
+  BindingTest() {}
+  ~BindingTest() override {}
 
-  binding.Close();
-  EXPECT_FALSE(called);
-  loop().RunUntilIdle();
-  EXPECT_TRUE(called);
-}
+ protected:
+  Environment env_;
+  RunLoop loop_;
+};
 
 // Tests that destroying a mojo::Binding closes the bound message pipe handle.
 TEST_F(BindingTest, DestroyClosesMessagePipe) {
@@ -87,87 +65,23 @@ TEST_F(BindingTest, DestroyClosesMessagePipe) {
     Binding<sample::Service> binding(&impl, request.Pass());
     ptr->Frobinate(nullptr, sample::Service::BAZ_OPTIONS_REGULAR, nullptr,
                    called_cb);
-    loop().RunUntilIdle();
+    loop_.RunUntilIdle();
     EXPECT_TRUE(called);
     EXPECT_FALSE(encountered_error);
   }
   // Now that the Binding is out of scope we should detect an error on the other
   // end of the pipe.
-  loop().RunUntilIdle();
+  loop_.RunUntilIdle();
   EXPECT_TRUE(encountered_error);
 
   // And calls should fail.
   called = false;
   ptr->Frobinate(nullptr, sample::Service::BAZ_OPTIONS_REGULAR, nullptr,
                  called_cb);
-  loop().RunUntilIdle();
-  EXPECT_FALSE(called);
-}
-
-// Tests that the binding's connection error handler gets called when the other
-// end is closed.
-TEST_F(BindingTest, ConnectionError) {
-  bool called = false;
-  {
-    ServiceImpl impl;
-    sample::ServicePtr ptr;
-    Binding<sample::Service> binding(&impl, GetProxy(&ptr));
-    binding.set_connection_error_handler([&called]() { called = true; });
-    ptr.reset();
-    EXPECT_FALSE(called);
-    loop().RunUntilIdle();
-    EXPECT_TRUE(called);
-    // We want to make sure that it isn't called again during destruction.
-    called = false;
-  }
-  EXPECT_FALSE(called);
-}
-
-// Tests that calling Close doesn't result in the connection error handler being
-// called.
-TEST_F(BindingTest, CloseDoesntCallConnectionErrorHandler) {
-  ServiceImpl impl;
-  sample::ServicePtr ptr;
-  Binding<sample::Service> binding(&impl, GetProxy(&ptr));
-  bool called = false;
-  binding.set_connection_error_handler([&called]() { called = true; });
-  binding.Close();
-  loop().RunUntilIdle();
-  EXPECT_FALSE(called);
-
-  // We can also close the other end, and the error handler still won't be
-  // called.
-  ptr.reset();
-  loop().RunUntilIdle();
+  loop_.RunUntilIdle();
   EXPECT_FALSE(called);
 }
 
-class ServiceImplWithBinding : public ServiceImpl {
- public:
-  ServiceImplWithBinding(bool* was_deleted,
-                         InterfaceRequest<sample::Service> request)
-      : ServiceImpl(was_deleted), binding_(this, request.Pass()) {
-    binding_.set_connection_error_handler([this]() { delete this; });
-  }
-
- private:
-  Binding<sample::Service> binding_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(ServiceImplWithBinding);
-};
-
-// Tests that the binding may be deleted in the connection error handler.
-TEST_F(BindingTest, SelfDeleteOnConnectionError) {
-  bool was_deleted = false;
-  sample::ServicePtr ptr;
-  // This should delete itself on connection error.
-  new ServiceImplWithBinding(&was_deleted, GetProxy(&ptr));
-  ptr.reset();
-  EXPECT_FALSE(was_deleted);
-  loop().RunUntilIdle();
-  EXPECT_TRUE(was_deleted);
-}
-
 // Tests that explicitly calling Unbind followed by rebinding works.
 TEST_F(BindingTest, Unbind) {
   ServiceImpl impl;
@@ -178,7 +92,7 @@ TEST_F(BindingTest, Unbind) {
   auto called_cb = [&called](int32_t result) { called = true; };
   ptr->Frobinate(nullptr, sample::Service::BAZ_OPTIONS_REGULAR, nullptr,
                  called_cb);
-  loop().RunUntilIdle();
+  loop_.RunUntilIdle();
   EXPECT_TRUE(called);
 
   called = false;
@@ -187,7 +101,7 @@ TEST_F(BindingTest, Unbind) {
   // All calls should fail when not bound...
   ptr->Frobinate(nullptr, sample::Service::BAZ_OPTIONS_REGULAR, nullptr,
                  called_cb);
-  loop().RunUntilIdle();
+  loop_.RunUntilIdle();
   EXPECT_FALSE(called);
 
   called = false;
@@ -196,25 +110,10 @@ TEST_F(BindingTest, Unbind) {
   // ...and should succeed again when the rebound.
   ptr->Frobinate(nullptr, sample::Service::BAZ_OPTIONS_REGULAR, nullptr,
                  called_cb);
-  loop().RunUntilIdle();
+  loop_.RunUntilIdle();
   EXPECT_TRUE(called);
 }
 
-class IntegerAccessorImpl : public sample::IntegerAccessor {
- public:
-  IntegerAccessorImpl() {}
-  ~IntegerAccessorImpl() override {}
-
- private:
-  // sample::IntegerAccessor implementation.
-  void GetInteger(const GetIntegerCallback& callback) override {
-    callback.Run(1, sample::ENUM_VALUE);
-  }
-  void SetInteger(int64_t data, sample::Enum type) override {}
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(IntegerAccessorImpl);
-};
-
 TEST_F(BindingTest, SetInterfacePtrVersion) {
   IntegerAccessorImpl impl;
   sample::IntegerAccessorPtr ptr;
@@ -222,102 +121,5 @@ TEST_F(BindingTest, SetInterfacePtrVersion) {
   EXPECT_EQ(3u, ptr.version());
 }
 
-// StrongBindingTest -----------------------------------------------------------
-
-using StrongBindingTest = BindingTestBase;
-
-// Tests that destroying a mojo::StrongBinding closes the bound message pipe
-// handle but does *not* destroy the implementation object.
-TEST_F(StrongBindingTest, DestroyClosesMessagePipe) {
-  bool encountered_error = false;
-  bool was_deleted = false;
-  ServiceImpl impl(&was_deleted);
-  sample::ServicePtr ptr;
-  auto request = GetProxy(&ptr);
-  ptr.set_connection_error_handler(
-      [&encountered_error]() { encountered_error = true; });
-  bool called = false;
-  auto called_cb = [&called](int32_t result) { called = true; };
-  {
-    StrongBinding<sample::Service> binding(&impl, request.Pass());
-    ptr->Frobinate(nullptr, sample::Service::BAZ_OPTIONS_REGULAR, nullptr,
-                   called_cb);
-    loop().RunUntilIdle();
-    EXPECT_TRUE(called);
-    EXPECT_FALSE(encountered_error);
-  }
-  // Now that the StrongBinding is out of scope we should detect an error on the
-  // other end of the pipe.
-  loop().RunUntilIdle();
-  EXPECT_TRUE(encountered_error);
-  // But destroying the StrongBinding doesn't destroy the object.
-  ASSERT_FALSE(was_deleted);
-}
-
-class ServiceImplWithStrongBinding : public ServiceImpl {
- public:
-  ServiceImplWithStrongBinding(bool* was_deleted,
-                               InterfaceRequest<sample::Service> request)
-      : ServiceImpl(was_deleted), binding_(this, request.Pass()) {}
-
-  StrongBinding<sample::Service>& binding() { return binding_; }
-
- private:
-  StrongBinding<sample::Service> binding_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(ServiceImplWithStrongBinding);
-};
-
-// Tests the typical case, where the implementation object owns the
-// StrongBinding (and should be destroyed on connection error).
-TEST_F(StrongBindingTest, ConnectionErrorDestroysImpl) {
-  sample::ServicePtr ptr;
-  bool was_deleted = false;
-  // Will delete itself.
-  new ServiceImplWithBinding(&was_deleted, GetProxy(&ptr));
-
-  loop().RunUntilIdle();
-  EXPECT_FALSE(was_deleted);
-
-  ptr.reset();
-  EXPECT_FALSE(was_deleted);
-  loop().RunUntilIdle();
-  EXPECT_TRUE(was_deleted);
-}
-
-// Tests that even when the implementation object owns the StrongBinding, that
-// the implementation can still be deleted (which should result in the message
-// pipe being closed). Also checks that the connection error handler doesn't get
-// called.
-TEST_F(StrongBindingTest, ExplicitDeleteImpl) {
-  bool ptr_error_handler_called = false;
-  sample::ServicePtr ptr;
-  auto request = GetProxy(&ptr);
-  ptr.set_connection_error_handler(
-      [&ptr_error_handler_called]() { ptr_error_handler_called = true; });
-  bool was_deleted = false;
-  ServiceImplWithStrongBinding* impl =
-      new ServiceImplWithStrongBinding(&was_deleted, request.Pass());
-  bool binding_error_handler_called = false;
-  impl->binding().set_connection_error_handler(
-      [&binding_error_handler_called]() {
-        binding_error_handler_called = true;
-      });
-
-  loop().RunUntilIdle();
-  EXPECT_FALSE(ptr_error_handler_called);
-  EXPECT_FALSE(was_deleted);
-
-  delete impl;
-  EXPECT_FALSE(ptr_error_handler_called);
-  EXPECT_TRUE(was_deleted);
-  was_deleted = false;  // It shouldn't be double-deleted!
-  loop().RunUntilIdle();
-  EXPECT_TRUE(ptr_error_handler_called);
-  EXPECT_FALSE(was_deleted);
-
-  EXPECT_FALSE(binding_error_handler_called);
-}
-
 }  // namespace
 }  // mojo
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/bindings_perftest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/bindings_perftest.cc
deleted file mode 100644
index 7440acc..0000000
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/bindings_perftest.cc
+++ /dev/null
@@ -1,127 +0,0 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "mojo/public/cpp/bindings/binding.h"
-#include "mojo/public/cpp/test_support/test_support.h"
-#include "mojo/public/cpp/test_support/test_utils.h"
-#include "mojo/public/cpp/utility/run_loop.h"
-#include "mojo/public/interfaces/bindings/tests/ping_service.mojom.h"
-#include "testing/gtest/include/gtest/gtest.h"
-
-namespace mojo {
-namespace {
-
-const double kMojoTicksPerSecond = 1000000.0;
-
-double MojoTicksToSeconds(MojoTimeTicks ticks) {
-  return ticks / kMojoTicksPerSecond;
-}
-
-class PingServiceImpl : public test::PingService {
- public:
-  explicit PingServiceImpl() {}
-  ~PingServiceImpl() override {}
-
-  // |PingService| methods:
-  void Ping(const Callback<void()>& callback) override;
-
- private:
-  MOJO_DISALLOW_COPY_AND_ASSIGN(PingServiceImpl);
-};
-
-void PingServiceImpl::Ping(const Callback<void()>& callback) {
-  callback.Run();
-}
-
-class PingPongTest {
- public:
-  explicit PingPongTest(test::PingServicePtr service);
-
-  void Run(unsigned int iterations);
-
- private:
-  void OnPingDone();
-
-  test::PingServicePtr service_;
-  unsigned int iterations_to_run_;
-  unsigned int current_iterations_;
-
-  MOJO_DISALLOW_COPY_AND_ASSIGN(PingPongTest);
-};
-
-PingPongTest::PingPongTest(test::PingServicePtr service)
-    : service_(service.Pass()) {
-}
-
-void PingPongTest::Run(unsigned int iterations) {
-  iterations_to_run_ = iterations;
-  current_iterations_ = 0;
-
-  service_->Ping([this]() { OnPingDone(); });
-  RunLoop::current()->Run();
-}
-
-void PingPongTest::OnPingDone() {
-  current_iterations_++;
-  if (current_iterations_ >= iterations_to_run_) {
-    RunLoop::current()->Quit();
-    return;
-  }
-
-  service_->Ping([this]() { OnPingDone(); });
-}
-
-struct BoundPingService {
-  BoundPingService() : binding(&impl) {
-    binding.Bind(GetProxy(&service));
-  }
-
-  PingServiceImpl impl;
-  test::PingServicePtr service;
-  Binding<test::PingService> binding;
-};
-
-class MojoBindingsPerftest : public testing::Test {
- protected:
-  Environment env_;
-  RunLoop run_loop_;
-};
-
-TEST_F(MojoBindingsPerftest, InProcessPingPong) {
-  test::PingServicePtr service;
-  PingServiceImpl impl;
-  Binding<test::PingService> binding(&impl, GetProxy(&service));
-  PingPongTest test(service.Pass());
-
-  {
-    const unsigned int kIterations = 100000;
-    const MojoTimeTicks start_time = MojoGetTimeTicksNow();
-    test.Run(kIterations);
-    const MojoTimeTicks end_time = MojoGetTimeTicksNow();
-    test::LogPerfResult(
-        "InProcessPingPong", "0_Inactive",
-        kIterations / MojoTicksToSeconds(end_time - start_time),
-        "pings/second");
-  }
-
-  {
-    const size_t kNumInactiveServices = 1000;
-    BoundPingService* inactive_services =
-        new BoundPingService[kNumInactiveServices];
-
-    const unsigned int kIterations = 10000;
-    const MojoTimeTicks start_time = MojoGetTimeTicksNow();
-    test.Run(kIterations);
-    const MojoTimeTicks end_time = MojoGetTimeTicksNow();
-    test::LogPerfResult(
-        "InProcessPingPong", "1000_Inactive",
-        kIterations / MojoTicksToSeconds(end_time - start_time),
-        "pings/second");
-
-    delete[] inactive_services;
-  }
-}
-
-}  // namespace
-}  // namespace mojo
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/callback_unittest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/callback_unittest.cc
index 158b21e..6b788fc 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/callback_unittest.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/callback_unittest.cc
@@ -44,24 +44,6 @@ struct RunnableMoveOnlyParam {
   int* calls;
 };
 
-int* g_calls = nullptr;
-
-void FunctionNoArgs() {
-  (*g_calls)++;
-}
-
-void FunctionOneArg(int increment) {
-  (*g_calls) += increment;
-}
-
-void FunctionStringArgByConstRef(const String& s) {
-  (*g_calls)++;
-}
-
-void FunctionMoveOnlyType(ExampleMoveOnlyType m) {
-  (*g_calls)++;
-}
-
 static_assert(!internal::HasCompatibleCallOperator<RunnableNoArgs>::value,
               "HasCompatibleCallOperator<Runnable>");
 static_assert(!internal::HasCompatibleCallOperator<RunnableOneArg, int>::value,
@@ -94,9 +76,8 @@ static_assert(internal::HasCompatibleCallOperator<decltype(lambda_four),
               "ExampleMoveOnlyType>");
 
 // Tests constructing and invoking a mojo::Callback from objects with a
-// compatible Run() method (called 'runnables'), from lambdas, and from function
-// pointers.
-TEST(Callback, Create) {
+// compatible Run() method (called 'runnables') and from lambdas.
+TEST(CallbackFromLambda, Create) {
   int calls = 0;
 
   RunnableNoArgs f(&calls);
@@ -140,55 +121,6 @@ TEST(Callback, Create) {
   cb_with_move_only_param = [&calls](ExampleMoveOnlyType m) { calls++; };
   cb_with_move_only_param.Run(m.Clone());
   EXPECT_EQ(8, calls);
-
-  // Construct from a function pointer.
-  g_calls = &calls;
-
-  cb = &FunctionNoArgs;
-  cb.Run();
-  EXPECT_EQ(9, calls);
-
-  cb_with_param = &FunctionOneArg;
-  cb_with_param.Run(1);
-  EXPECT_EQ(10, calls);
-
-  cb_with_string_param = &FunctionStringArgByConstRef;
-  cb_with_string_param.Run(String("hello"));
-  EXPECT_EQ(11, calls);
-
-  cb_with_move_only_param = &FunctionMoveOnlyType;
-  cb_with_move_only_param.Run(m.Clone());
-  EXPECT_EQ(12, calls);
-
-  g_calls = nullptr;
-}
-
-bool g_overloaded_function_with_int_param_called = false;
-
-void OverloadedFunction(int param) {
-  g_overloaded_function_with_int_param_called = true;
-}
-
-bool g_overloaded_function_with_double_param_called = false;
-
-void OverloadedFunction(double param) {
-  g_overloaded_function_with_double_param_called = true;
-}
-
-// Tests constructing and invoking a mojo::Callback from pointers to overloaded
-// functions.
-TEST(Callback, CreateFromOverloadedFunctionPtr) {
-  g_overloaded_function_with_int_param_called = false;
-  mojo::Callback<void(int)> cb_with_int_param = &OverloadedFunction;
-  cb_with_int_param.Run(123);
-  EXPECT_TRUE(g_overloaded_function_with_int_param_called);
-  g_overloaded_function_with_int_param_called = false;
-
-  g_overloaded_function_with_double_param_called = false;
-  mojo::Callback<void(double)> cb_with_double_param = &OverloadedFunction;
-  cb_with_double_param.Run(123);
-  EXPECT_TRUE(g_overloaded_function_with_double_param_called);
-  g_overloaded_function_with_double_param_called = false;
 }
 
 }  // namespace
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/connector_unittest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/connector_unittest.cc
index aab5a39..b5e3405 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/connector_unittest.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/connector_unittest.cc
@@ -7,7 +7,7 @@
 
 #include "mojo/public/cpp/bindings/lib/connector.h"
 #include "mojo/public/cpp/bindings/lib/message_builder.h"
-#include "mojo/public/cpp/bindings/tests/message_queue.h"
+#include "mojo/public/cpp/bindings/lib/message_queue.h"
 #include "mojo/public/cpp/environment/environment.h"
 #include "mojo/public/cpp/system/macros.h"
 #include "mojo/public/cpp/utility/run_loop.h"
@@ -31,7 +31,7 @@ class MessageAccumulator : public MessageReceiver {
   void Pop(Message* message) { queue_.Pop(message); }
 
  private:
-  MessageQueue queue_;
+  internal::MessageQueue queue_;
 };
 
 class ConnectorDeletingMessageAccumulator : public MessageAccumulator {
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc
index 681cc6d..6486192 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/interface_ptr_unittest.cc
@@ -192,13 +192,6 @@ class InterfacePtrTest : public testing::Test {
   RunLoop loop_;
 };
 
-TEST_F(InterfacePtrTest, IsBound) {
-  math::CalculatorPtr calc;
-  EXPECT_FALSE(calc.is_bound());
-  MathCalculatorImpl calc_impl(GetProxy(&calc));
-  EXPECT_TRUE(calc.is_bound());
-}
-
 TEST_F(InterfacePtrTest, EndToEnd) {
   math::CalculatorPtr calc;
   MathCalculatorImpl calc_impl(GetProxy(&calc));
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/request_response_unittest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/request_response_unittest.cc
index 8bfeb5d..f7c3cf6 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/request_response_unittest.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/request_response_unittest.cc
@@ -2,7 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "mojo/public/cpp/bindings/binding.h"
 #include "mojo/public/cpp/environment/environment.h"
 #include "mojo/public/cpp/test_support/test_utils.h"
 #include "mojo/public/cpp/utility/run_loop.h"
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/router_unittest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/router_unittest.cc
index 7aeb414..def9ceb 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/router_unittest.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/router_unittest.cc
@@ -6,8 +6,8 @@
 #include <string.h>
 
 #include "mojo/public/cpp/bindings/lib/message_builder.h"
+#include "mojo/public/cpp/bindings/lib/message_queue.h"
 #include "mojo/public/cpp/bindings/lib/router.h"
-#include "mojo/public/cpp/bindings/tests/message_queue.h"
 #include "mojo/public/cpp/environment/environment.h"
 #include "mojo/public/cpp/system/macros.h"
 #include "mojo/public/cpp/utility/run_loop.h"
@@ -36,7 +36,7 @@ void AllocResponseMessage(uint32_t name,
 
 class MessageAccumulator : public MessageReceiver {
  public:
-  explicit MessageAccumulator(MessageQueue* queue) : queue_(queue) {}
+  explicit MessageAccumulator(internal::MessageQueue* queue) : queue_(queue) {}
 
   bool Accept(Message* message) override {
     queue_->Push(message);
@@ -44,7 +44,7 @@ class MessageAccumulator : public MessageReceiver {
   }
 
  private:
-  MessageQueue* queue_;
+  internal::MessageQueue* queue_;
 };
 
 class ResponseGenerator : public MessageReceiverWithResponderStatus {
@@ -152,7 +152,7 @@ TEST_F(RouterTest, BasicRequestResponse) {
   Message request;
   AllocRequestMessage(1, "hello", &request);
 
-  MessageQueue message_queue;
+  internal::MessageQueue message_queue;
   router0.AcceptWithResponder(&request, new MessageAccumulator(&message_queue));
 
   PumpMessages();
@@ -192,7 +192,7 @@ TEST_F(RouterTest, BasicRequestResponse_Synchronous) {
   Message request;
   AllocRequestMessage(1, "hello", &request);
 
-  MessageQueue message_queue;
+  internal::MessageQueue message_queue;
   router0.AcceptWithResponder(&request, new MessageAccumulator(&message_queue));
 
   router1.WaitForIncomingMessage(MOJO_DEADLINE_INDEFINITE);
@@ -234,7 +234,7 @@ TEST_F(RouterTest, RequestWithNoReceiver) {
   Message request;
   AllocRequestMessage(1, "hello", &request);
 
-  MessageQueue message_queue;
+  internal::MessageQueue message_queue;
   router0.AcceptWithResponder(&request, new MessageAccumulator(&message_queue));
 
   PumpMessages();
@@ -256,7 +256,7 @@ TEST_F(RouterTest, LazyResponses) {
   Message request;
   AllocRequestMessage(1, "hello", &request);
 
-  MessageQueue message_queue;
+  internal::MessageQueue message_queue;
   router0.AcceptWithResponder(&request, new MessageAccumulator(&message_queue));
   PumpMessages();
 
@@ -311,7 +311,7 @@ TEST_F(RouterTest, MissingResponses) {
   Message request;
   AllocRequestMessage(1, "hello", &request);
 
-  MessageQueue message_queue;
+  internal::MessageQueue message_queue;
   router0.AcceptWithResponder(&request, new MessageAccumulator(&message_queue));
   PumpMessages();
 
@@ -354,7 +354,7 @@ TEST_F(RouterTest, LateResponse) {
     Message request;
     AllocRequestMessage(1, "hello", &request);
 
-    MessageQueue message_queue;
+    internal::MessageQueue message_queue;
     router0.AcceptWithResponder(&request,
                                 new MessageAccumulator(&message_queue));
 
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/validation_unittest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/validation_unittest.cc
index 39befaf..9b4e271 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/validation_unittest.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/validation_unittest.cc
@@ -9,7 +9,7 @@
 #include <vector>
 
 #include "mojo/public/c/system/macros.h"
-#include "mojo/public/cpp/bindings/binding.h"
+#include "mojo/public/cpp/bindings/interface_impl.h"
 #include "mojo/public/cpp/bindings/interface_ptr.h"
 #include "mojo/public/cpp/bindings/lib/connector.h"
 #include "mojo/public/cpp/bindings/lib/filter_chain.h"
diff --git a/third_party/mojo/src/mojo/public/dart/.analysis_options b/third_party/mojo/src/mojo/public/dart/.analysis_options
deleted file mode 100644
index 4886c56..0000000
--- a/third_party/mojo/src/mojo/public/dart/.analysis_options
+++ /dev/null
@@ -1,3 +0,0 @@
-analyzer:
-  exclude:
-    - 'sdk_ext/**'
diff --git a/third_party/mojo/src/mojo/public/dart/.gitignore b/third_party/mojo/src/mojo/public/dart/.gitignore
index d0a207a..3b66ccd 100644
--- a/third_party/mojo/src/mojo/public/dart/.gitignore
+++ b/third_party/mojo/src/mojo/public/dart/.gitignore
@@ -1,4 +1,2 @@
-lib/_sdkext
-.packages
 packages/
 pubspec.lock
diff --git a/third_party/mojo/src/mojo/public/dart/BUILD.gn b/third_party/mojo/src/mojo/public/dart/BUILD.gn
index fb14555..b820d96 100644
--- a/third_party/mojo/src/mojo/public/dart/BUILD.gn
+++ b/third_party/mojo/src/mojo/public/dart/BUILD.gn
@@ -21,6 +21,10 @@ dart_mojo_sdk_sources = [
   "lib/src/stub.dart",
   "lib/src/union.dart",
   "lib/src/types.dart",
+  "sdk_ext/internal.dart",
+  "sdk_ext/src/handle_watcher.dart",
+  "sdk_ext/src/natives.dart",
+  "sdk_ext/src/timer_queue.dart",
 ]
 
 dartzip_package("dart") {
@@ -45,9 +49,6 @@ dart_pkg("mojo") {
               "README.md",
             ]
 
-  sdk_ext_directory = "sdk_ext"
-  sdk_ext_mappings = [ "dart:mojo.internal,internal.dart" ]
-
   # List of mojom targets that the mojo pkg exports
   deps = [
     "../interfaces",
diff --git a/third_party/mojo/src/mojo/public/dart/CHANGELOG.md b/third_party/mojo/src/mojo/public/dart/CHANGELOG.md
index 03b981d..dcb340c 100644
--- a/third_party/mojo/src/mojo/public/dart/CHANGELOG.md
+++ b/third_party/mojo/src/mojo/public/dart/CHANGELOG.md
@@ -1,23 +1,3 @@
-## 0.0.18
-
-  - 89 changes: https://github.com/domokit/mojo/compare/0fd4d06...c3119f6
-
-## 0.0.17
-
-  - 18 changes: https://github.com/domokit/mojo/compare/e7433cf...8879bfd
-
-## 0.0.16
-
-  - 27 changes: https://github.com/domokit/mojo/compare/e028733...e7433cf
-
-## 0.0.15
-
-  - 6 changes: https://github.com/domokit/mojo/compare/4df2d39...e028733
-
-## 0.0.14
-
-  - 138 changes: https://github.com/domokit/mojo/compare/850ac24...cf84c48
-
 ## 0.0.13
 
   - 70 changes: https://github.com/domokit/mojo/compare/889091e...136e0d4
diff --git a/third_party/mojo/src/mojo/public/dart/lib/io.dart b/third_party/mojo/src/mojo/public/dart/lib/io.dart
new file mode 100644
index 0000000..bb8e64dc
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/dart/lib/io.dart
@@ -0,0 +1,49 @@
+// Copyright 2015 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+library dart.io;
+
+import 'dart:async';
+import 'dart:collection' show HashMap,
+                              HashSet,
+                              Queue,
+                              ListQueue,
+                              LinkedList,
+                              LinkedListEntry,
+                              UnmodifiableMapView;
+import 'dart:convert';
+import 'dart:isolate';
+import 'dart:math';
+import 'dart:typed_data';
+
+
+part '../../../../dart/sdk/lib/io/bytes_builder.dart';
+part '../../../../dart/sdk/lib/io/common.dart';
+part '../../../../dart/sdk/lib/io/crypto.dart';
+part '../../../../dart/sdk/lib/io/data_transformer.dart';
+part '../../../../dart/sdk/lib/io/directory.dart';
+part '../../../../dart/sdk/lib/io/directory_impl.dart';
+part '../../../../dart/sdk/lib/io/file.dart';
+part '../../../../dart/sdk/lib/io/file_impl.dart';
+part '../../../../dart/sdk/lib/io/file_system_entity.dart';
+part '../../../../dart/sdk/lib/io/http.dart';
+part '../../../../dart/sdk/lib/io/http_date.dart';
+part '../../../../dart/sdk/lib/io/http_headers.dart';
+part '../../../../dart/sdk/lib/io/http_impl.dart';
+part '../../../../dart/sdk/lib/io/http_parser.dart';
+part '../../../../dart/sdk/lib/io/http_session.dart';
+part '../../../../dart/sdk/lib/io/io_sink.dart';
+part '../../../../dart/sdk/lib/io/io_service.dart';
+part '../../../../dart/sdk/lib/io/link.dart';
+part '../../../../dart/sdk/lib/io/platform.dart';
+part '../../../../dart/sdk/lib/io/platform_impl.dart';
+part '../../../../dart/sdk/lib/io/process.dart';
+part '../../../../dart/sdk/lib/io/service_object.dart';
+part '../../../../dart/sdk/lib/io/socket.dart';
+part '../../../../dart/sdk/lib/io/stdio.dart';
+part '../../../../dart/sdk/lib/io/string_transformer.dart';
+part '../../../../dart/sdk/lib/io/secure_socket.dart';
+part '../../../../dart/sdk/lib/io/secure_server_socket.dart';
+part '../../../../dart/sdk/lib/io/websocket.dart';
+part '../../../../dart/sdk/lib/io/websocket_impl.dart';
diff --git a/third_party/mojo/src/mojo/public/dart/pubspec.yaml b/third_party/mojo/src/mojo/public/dart/pubspec.yaml
index bdcad2e..3944b34 100644
--- a/third_party/mojo/src/mojo/public/dart/pubspec.yaml
+++ b/third_party/mojo/src/mojo/public/dart/pubspec.yaml
@@ -4,4 +4,4 @@ dependencies:
 description: Dart files to support executing inside Mojo.
 homepage: https://github.com/domokit/mojo
 name: mojo
-version: 0.0.18
+version: 0.0.13
diff --git a/third_party/mojo/src/mojo/public/dart/rules.gni b/third_party/mojo/src/mojo/public/dart/rules.gni
index d4adbb1..36fc92d 100644
--- a/third_party/mojo/src/mojo/public/dart/rules.gni
+++ b/third_party/mojo/src/mojo/public/dart/rules.gni
@@ -116,6 +116,8 @@ template("dartzip_package") {
       rebase_path(package_output),
       rebase_path("$target_gen_dir/${package_target_name}_analyze.stamp"),
       "--no-hints",
+      "--url-mapping=dart:io,/" +
+          rebase_path("mojo/public/dart/lib/io.dart", "/", mojo_sdk_root),
     ]
 
     deps = [
@@ -224,12 +226,6 @@ template("dartzip_packaged_application") {
 #   sdk_ext_directory (optional)
 #       Directory containing sdk-ext .dart sources.
 #
-#   sdk_ext_files (optional)
-#       List of sources to include in sdk-ext.
-#
-#   sdk_ext_mappings (optional)
-#       Mappings for dart libraries that are part of of sdk_ext.
-#
 template("dart_pkg") {
   if (defined(invoker.pkg_dir)) {
     pubspec_yaml_path = rebase_path("pubspec.yaml", "", invoker.pkg_dir)
@@ -249,7 +245,6 @@ template("dart_pkg") {
   pkg_directory = rebase_path("$root_gen_dir/dart-pkg")
   package_root = rebase_path("$root_gen_dir/dart-pkg/packages")
   stamp_file = "$root_gen_dir/dart-pkg/${package_name}.stamp"
-  output_dir = "$root_gen_dir/dart-pkg/${package_name}"
 
   assert(defined(invoker.sources) || defined(invoker.pkg_dir))
 
@@ -283,19 +278,8 @@ template("dart_pkg") {
       sdk_ext_directory += [ invoker.sdk_ext_directory ]
     }
 
-    sdk_ext_files = []
-    if (defined(invoker.sdk_ext_files)) {
-      sdk_ext_files += invoker.sdk_ext_files
-    }
-
-    sdk_ext_mappings = []
-    if (defined(invoker.sdk_ext_mappings)) {
-      sdk_ext_mappings += invoker.sdk_ext_mappings
-    }
-
     script = rebase_path("mojo/public/tools/dart_pkg.py", ".", mojo_sdk_root)
     outputs = [
-      output_dir,
       stamp_file,
     ]
 
@@ -331,8 +315,6 @@ template("dart_pkg") {
              "--package-sources",
            ] + rebase_path(sources) + [ "--mojom-sources" ] +
            rebase_path(mojom_sources, "", mojo_sdk_root) +
-           [ "--sdk-ext-directories" ] + rebase_path(sdk_ext_directory) +
-           [ "--sdk-ext-files" ] + rebase_path(sdk_ext_files) +
-           [ "--sdk-ext-mappings" ] + sdk_ext_mappings
+           [ "--sdk-ext-directories" ] + rebase_path(sdk_ext_directory)
   }
 }
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/BUILD.gn b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/BUILD.gn
index e7efd3d..9bf206c 100644
--- a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/BUILD.gn
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/BUILD.gn
@@ -9,7 +9,6 @@ mojom("test_interfaces") {
   sources = [
     "math_calculator.mojom",
     "no_module.mojom",
-    "ping_service.mojom",
     "rect.mojom",
     "regression_tests.mojom",
     "sample_factory.mojom",
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/ping_service.mojom b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/ping_service.mojom
deleted file mode 100644
index 3e1f1c4..0000000
--- a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/ping_service.mojom
+++ /dev/null
@@ -1,10 +0,0 @@
-// Copyright 2015 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-[JavaPackage="org.chromium.mojo.bindings.test.mojom.ping"]
-module mojo.test;
-
-interface PingService {
-  Ping() => ();
-};
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/test_unions.mojom b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/test_unions.mojom
index e998f47..6e631b2 100644
--- a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/test_unions.mojom
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/test_unions.mojom
@@ -69,7 +69,6 @@ struct SmallStructNonNullableUnion {
 
 struct SmallObjStruct {
   ObjectUnion obj_union;
-  int8 f_int8;
 };
 
 interface SmallCache {
@@ -85,12 +84,3 @@ struct TryNonNullStruct {
   DummyStruct? nullable;
   DummyStruct non_nullable;
 };
-
-union OldUnion {
-  int8 f_int8;
-};
-
-union NewUnion {
-  int8 f_int8;
-  int16 f_int16;
-};
diff --git a/third_party/mojo/src/mojo/public/mojo_application.gni b/third_party/mojo/src/mojo/public/mojo_application.gni
index 32bdb7a..7ab5a31 100644
--- a/third_party/mojo/src/mojo/public/mojo_application.gni
+++ b/third_party/mojo/src/mojo/public/mojo_application.gni
@@ -20,7 +20,6 @@ template("mojo_native_application") {
   if (!is_nacl) {
     output = base_target_name + ".mojo"
     library_target_name = base_target_name + "_library"
-    copy_symbols_target = "__${final_target_name}_copy_symbols"
 
     if (is_linux || is_android) {
       library_name = "lib${library_target_name}.so"
@@ -131,27 +130,7 @@ template("mojo_native_application") {
         testonly = invoker.testonly
       }
 
-      visibility = [
-        ":${final_target_name}",
-        ":${copy_symbols_target}",
-      ]
-    }
-
-    copy(copy_symbols_target) {
-      if (defined(invoker.testonly)) {
-        testonly = invoker.testonly
-      }
       visibility = [ ":${final_target_name}" ]
-      deps = [
-        ":${library_target_name}",
-      ]
-
-      sources = [
-        "${root_out_dir}/${library_name}",
-      ]
-      outputs = [
-        "${root_out_dir}/symbols/${library_name}",
-      ]
     }
 
     copy(final_target_name) {
@@ -163,7 +142,6 @@ template("mojo_native_application") {
       }
       deps = [
         ":${library_target_name}",
-        ":${copy_symbols_target}",
       ]
 
       sources = [
@@ -311,111 +289,30 @@ template("mojo_native_application") {
 }
 
 if (is_android) {
-  import("//build/config/android/rules.gni")
-
   # Declares an Android Mojo application consisting of an .so file and a
   # corresponding .dex.jar file.
   #
   # Variables:
-  #   sources (optional): The c++ sources.
-  #   deps (optional): The c++ dependencies.
-  #   java_sources (optional): The java sources.
-  #   java_deps (optional): The java dependencies.
-  #   jni_package (optional): The c++ package for the generated jni headers.
+  #   input_so: the .so file to bundle
+  #   input_dex_jar: the .dex.jar file to bundle
+  #   deps / public_deps / data_deps (optional):
+  #       Dependencies. The targets that generate the .so/jar inputs should be
+  #       listed in either deps or public_deps.
   #   output_name (optional): override for the output file name
-  #   public_deps / data_deps (optional): Dependencies.
   template("mojo_android_application") {
-    shared_library_name = "__${target_name}_lib"
-    library_basename = "lib${shared_library_name}.so"
-    if (defined(invoker.jni_package)) {
-      assert(defined(invoker.java_sources))
-      generate_jni_name = "__${target_name}_jni"
-    }
-    if (defined(invoker.java_sources)) {
-      java_library_name = "__${target_name}_java"
-    }
-    android_standalone_library_name = "__${target_name}_java_lib"
-    dex_output_path = "${target_gen_dir}/${target_name}.dex.jar"
-    zip_action_name = "__${target_name}_zip"
-    zip_action_output = "${target_gen_dir}/${target_name}.zip"
-    copy_symbols_target = "__${target_name}_copy_symbols"
-    final_target_name = target_name
-
-    if (defined(invoker.jni_package)) {
-      generate_jni(generate_jni_name) {
-        visibility = [ ":${shared_library_name}" ]
-
-        sources = invoker.java_sources
-        jni_package = invoker.jni_package
-      }
-    }
-
-    shared_library(shared_library_name) {
-      visibility = [
-        ":${copy_symbols_target}",
-        ":${zip_action_name}",
-      ]
-
-      if (defined(invoker.sources)) {
-        sources = invoker.sources
-      }
-
-      deps = []
-      if (defined(invoker.jni_package)) {
-        deps += [ ":${generate_jni_name}" ]
-      }
-      if (defined(invoker.deps)) {
-        deps += invoker.deps
-      }
-    }
-
-    copy(copy_symbols_target) {
-      visibility = [ ":${final_target_name}" ]
-      deps = [
-        ":${shared_library_name}",
-      ]
-
-      sources = [
-        "${root_out_dir}/${library_basename}",
-      ]
-      outputs = [
-        "${root_out_dir}/symbols/${library_basename}",
-      ]
-    }
-
-    if (defined(invoker.java_sources)) {
-      android_library(java_library_name) {
-        visibility = [ ":*" ]
-
-        java_files = invoker.java_sources
-
-        if (defined(invoker.java_deps)) {
-          deps = invoker.java_deps
-        }
-      }
-    }
-
-    android_standalone_library(android_standalone_library_name) {
-      deps = []
-
-      if (defined(invoker.java_sources)) {
-        deps += [ ":${java_library_name}" ]
-      }
-
-      if (defined(invoker.java_deps)) {
-        deps += invoker.java_deps
-      }
-
-      dex_path = dex_output_path
-    }
+    assert(defined(invoker.input_so))
+    assert(defined(invoker.input_dex_jar))
 
+    zip_action_name = "${target_name}_zip"
+    zip_action_output = "$target_gen_dir/${target_name}.zip"
+    prepend_action_name = target_name
     action(zip_action_name) {
-      visibility = [ ":${final_target_name}" ]
+      visibility = [ ":$prepend_action_name" ]
       script = "//build/android/gn/zip.py"
 
       inputs = [
-        "${root_out_dir}/lib.stripped/${library_basename}",
-        dex_output_path,
+        invoker.input_so,
+        invoker.input_dex_jar,
       ]
 
       output = zip_action_output
@@ -426,8 +323,8 @@ if (is_android) {
       rebase_inputs = rebase_path(inputs, root_build_dir)
       rebase_output = rebase_path(output, root_build_dir)
       args = [
-        "--inputs=${rebase_inputs}",
-        "--output=${rebase_output}",
+        "--inputs=$rebase_inputs",
+        "--output=$rebase_output",
       ]
 
       if (defined(invoker.deps)) {
@@ -442,12 +339,12 @@ if (is_android) {
     }
 
     if (defined(invoker.output_name)) {
-      mojo_output = "${root_out_dir}/" + invoker.output_name + ".mojo"
+      mojo_output = "$root_out_dir/" + invoker.output_name + ".mojo"
     } else {
-      mojo_output = "${root_out_dir}/" + target_name + ".mojo"
+      mojo_output = "$root_out_dir/" + target_name + ".mojo"
     }
 
-    action(final_target_name) {
+    action(target_name) {
       script = rebase_path("mojo/public/tools/prepend.py", ".", mojo_root)
 
       input = zip_action_output
@@ -463,17 +360,13 @@ if (is_android) {
       rebase_input = rebase_path(input, root_build_dir)
       rebase_output = rebase_path(output, root_build_dir)
       args = [
-        "--input=${rebase_input}",
-        "--output=${rebase_output}",
+        "--input=$rebase_input",
+        "--output=$rebase_output",
         "--line=#!mojo mojo:android_handler",
       ]
 
-      deps = [
-        ":${copy_symbols_target}",
-      ]
-
       public_deps = [
-        ":${zip_action_name}",
+        ":$zip_action_name",
       ]
     }
   }
diff --git a/third_party/mojo/src/mojo/public/python/mojo_bindings/descriptor.py b/third_party/mojo/src/mojo/public/python/mojo_bindings/descriptor.py
index c359e44..efba73d 100644
--- a/third_party/mojo/src/mojo/public/python/mojo_bindings/descriptor.py
+++ b/third_party/mojo/src/mojo/public/python/mojo_bindings/descriptor.py
@@ -34,13 +34,6 @@ class Type(object):
     """
     return self.Convert(value)
 
-  def IsUnion(self):
-    """
-    Returns true if the type is a union. This is necessary to be able to
-    identify a union when descriptor.py cannot be imported.
-    """
-    return False
-
 
 class SerializableType(Type):
   """Describe a type that can be serialized by itself."""
@@ -160,47 +153,6 @@ class FloatType(NumericType):
     return float(value)
 
 
-class UnionType(SerializableType):
-  """Base Type object for union."""
-
-  def __init__(self, union_type_getter, nullable=False):
-    SerializableType.__init__(self, 'IIQ')
-    self.nullable = nullable
-    self._union_type_getter = union_type_getter
-    self._union_type = None
-
-  def IsUnion(self):
-    return True
-
-  @property
-  def union_type(self):
-    if not self._union_type:
-      self._union_type = self._union_type_getter()
-    return self._union_type
-
-  def Serialize(self, value, data_offset, data, handle_offset):
-    if not value:
-      if not self.nullable:
-        raise serialization.SerializationException(
-            'Trying to serialize null for non nullable type.')
-      return ((0, 0, 0), [])
-
-    ((size, tag, entry, new_data), new_handles) = (
-        value.SerializeInline(handle_offset))
-    if len(new_data) > 0:
-      data.extend(new_data)
-      entry = data_offset - 8
-
-    return ((size, tag, entry), new_handles)
-
-  def Deserialize(self, value, context):
-    result = self.union_type.Deserialize(context)
-    if not result and not self.nullable:
-      raise serialization.DeserializationException(
-          'Trying to deserialize null for non nullable type.')
-    return result
-
-
 class PointerType(SerializableType):
   """Base Type object for pointers."""
 
@@ -482,19 +434,16 @@ class GenericArrayType(BaseArrayType):
       to_pack.extend(serialization.Flatten(new_data))
       returned_handles.extend(new_handles)
       position = position + self.sub_type.GetByteSize()
-
     serialization.HEADER_STRUCT.pack_into(data, data_end, size, len(value))
-    # TODO(azani): Refactor so we don't have to create big formatting strings.
-    struct.pack_into(('%s' % self.sub_type.GetTypeCode()) * len(value),
+    struct.pack_into('%d%s' % (len(value), self.sub_type.GetTypeCode()),
                      data,
                      data_end + serialization.HEADER_STRUCT.size,
                      *to_pack)
     return (data_offset, returned_handles)
 
   def DeserializeArray(self, size, nb_elements, context):
-    # TODO(azani): Refactor so the format string isn't so big.
     values = struct.unpack_from(
-        nb_elements * self.sub_type.GetTypeCode(),
+        '%d%s' % (nb_elements, self.sub_type.GetTypeCode()),
         buffer(context.data, serialization.HEADER_STRUCT.size))
     values_per_element = len(self.sub_type.GetTypeCode())
     assert nb_elements * values_per_element == len(values)
diff --git a/third_party/mojo/src/mojo/public/python/mojo_bindings/reflection.py b/third_party/mojo/src/mojo/public/python/mojo_bindings/reflection.py
index cfd7e64..6c4767b 100644
--- a/third_party/mojo/src/mojo/public/python/mojo_bindings/reflection.py
+++ b/third_party/mojo/src/mojo/public/python/mojo_bindings/reflection.py
@@ -135,103 +135,6 @@ class MojoStructType(type):
     raise AttributeError('can\'t delete attribute')
 
 
-class MojoUnionType(type):
-
-  def __new__(mcs, name, bases, dictionary):
-    dictionary['__slots__'] = ('_cur_field', '_data')
-    descriptor = dictionary.pop('DESCRIPTOR', {})
-
-    fields = descriptor.get('fields', [])
-    def _BuildUnionProperty(field):
-
-      # pylint: disable=W0212
-      def Get(self):
-        if self._cur_field != field:
-          raise AttributeError('%s is not currently set' % field.name,
-              field.name, self._cur_field.name)
-        return self._data
-
-      # pylint: disable=W0212
-      def Set(self, value):
-        self._cur_field = field
-        self._data = field.field_type.Convert(value)
-
-      return property(Get, Set)
-
-    for field in fields:
-      dictionary[field.name] = _BuildUnionProperty(field)
-
-    def UnionInit(self, **kwargs):
-      self.SetInternals(None, None)
-      items = kwargs.items()
-      if len(items) == 0:
-        return
-
-      if len(items) > 1:
-        raise TypeError('only 1 member may be set on a union.')
-
-      setattr(self, items[0][0], items[0][1])
-    dictionary['__init__'] = UnionInit
-
-    serializer = serialization.UnionSerializer(fields)
-    def SerializeUnionInline(self, handle_offset=0):
-      return serializer.SerializeInline(self, handle_offset)
-    dictionary['SerializeInline'] = SerializeUnionInline
-
-    def SerializeUnion(self, handle_offset=0):
-      return serializer.Serialize(self, handle_offset)
-    dictionary['Serialize'] = SerializeUnion
-
-    def DeserializeUnion(cls, context):
-      return serializer.Deserialize(context, cls)
-    dictionary['Deserialize'] = classmethod(DeserializeUnion)
-
-    class Tags(object):
-      __metaclass__ = MojoEnumType
-      VALUES = [(field.name, field.index) for field in fields]
-    dictionary['Tags'] = Tags
-
-    def GetTag(self):
-      return self._cur_field.index
-    dictionary['tag'] = property(GetTag, None)
-
-    def GetData(self):
-      return self._data
-    dictionary['data'] = property(GetData, None)
-
-    def IsUnknown(self):
-      return not self._cur_field
-    dictionary['IsUnknown'] = IsUnknown
-
-    def UnionEq(self, other):
-      return (
-          (type(self) is type(other))
-          and (self.tag == other.tag)
-          and (self.data == other.data))
-    dictionary['__eq__'] = UnionEq
-
-    def UnionNe(self, other):
-      return not self.__eq__(other)
-    dictionary['__ne__'] = UnionNe
-
-    def UnionStr(self):
-      return '<%s.%s(%s): %s>' % (
-          self.__class__.__name__,
-          self._cur_field.name,
-          self.tag,
-          self.data)
-    dictionary['__str__'] = UnionStr
-    dictionary['__repr__'] = UnionStr
-
-    def SetInternals(self, field, data):
-      self._cur_field = field
-      self._data = data
-    dictionary['SetInternals'] = SetInternals
-
-
-    return type.__new__(mcs, name, bases, dictionary)
-
-
 class InterfaceRequest(object):
   """
   An interface request allows to send a request for an interface to a remote
diff --git a/third_party/mojo/src/mojo/public/python/mojo_bindings/serialization.py b/third_party/mojo/src/mojo/public/python/mojo_bindings/serialization.py
index b1a35ec..32f60f0 100644
--- a/third_party/mojo/src/mojo/public/python/mojo_bindings/serialization.py
+++ b/third_party/mojo/src/mojo/public/python/mojo_bindings/serialization.py
@@ -7,12 +7,9 @@
 import struct
 
 
-# Format of a header for a struct, array or union.
+# Format of a header for a struct or an array.
 HEADER_STRUCT = struct.Struct("<II")
 
-# Format for a pointer.
-POINTER_STRUCT = struct.Struct("<Q")
-
 
 def Flatten(value):
   """Flattens nested lists/tuples into an one-level list. If value is not a
@@ -221,89 +218,3 @@ def _GetStruct(groups):
   if alignment_needed:
     codes.append('x' * alignment_needed)
   return struct.Struct(''.join(codes))
-
-
-class UnionSerializer(object):
-  """
-  Helper class to serialize/deserialize a union.
-  """
-  def __init__(self, fields):
-    self._fields = {field.index: field for field in fields}
-
-  def SerializeInline(self, union, handle_offset):
-    data = bytearray()
-    field = self._fields[union.tag]
-
-    # If the union value is a simple type or a nested union, it is returned as
-    # entry.
-    # Otherwise, the serialized value is appended to data and the value of entry
-    # is -1. The caller will need to set entry to the location where the
-    # caller will append data.
-    (entry, handles) = field.field_type.Serialize(
-        union.data, -1, data, handle_offset)
-
-    # If the value contained in the union is itself a union, we append its
-    # serialized value to data and set entry to -1. The caller will need to set
-    # entry to the location where the caller will append data.
-    if field.field_type.IsUnion():
-      nested_union = bytearray(16)
-      HEADER_STRUCT.pack_into(nested_union, 0, entry[0], entry[1])
-      POINTER_STRUCT.pack_into(nested_union, 8, entry[2])
-
-      data = nested_union + data
-
-      # Since we do not know where the caller will append the nested union,
-      # we set entry to an invalid value and let the caller figure out the right
-      # value.
-      entry = -1
-
-    return (16, union.tag, entry, data), handles
-
-  def Serialize(self, union, handle_offset):
-    (size, tag, entry, extra_data), handles = self.SerializeInline(
-        union, handle_offset)
-    data = bytearray(16)
-    if extra_data:
-      entry = 8
-    data.extend(extra_data)
-
-    field = self._fields[union.tag]
-
-    HEADER_STRUCT.pack_into(data, 0, size, tag)
-    typecode = field.GetTypeCode()
-
-    # If the value is a nested union, we store a 64 bits pointer to it.
-    if field.field_type.IsUnion():
-      typecode = 'Q'
-
-    struct.pack_into('<%s' % typecode, data, 8, entry)
-    return data, handles
-
-  def Deserialize(self, context, union_class):
-    if len(context.data) < HEADER_STRUCT.size:
-      raise DeserializationException(
-          'Available data too short to contain header.')
-    (size, tag) = HEADER_STRUCT.unpack_from(context.data)
-
-    if size == 0:
-      return None
-
-    if size != 16:
-      raise DeserializationException('Invalid union size %s' % size)
-
-    union = union_class.__new__(union_class)
-    if tag not in self._fields:
-      union.SetInternals(None, None)
-      return union
-
-    field = self._fields[tag]
-    if field.field_type.IsUnion():
-      ptr = POINTER_STRUCT.unpack_from(context.data, 8)[0]
-      value = field.field_type.Deserialize(ptr, context.GetSubContext(ptr+8))
-    else:
-      raw_value = struct.unpack_from(
-          field.GetTypeCode(), context.data, 8)[0]
-      value = field.field_type.Deserialize(raw_value, context.GetSubContext(8))
-
-    union.SetInternals(field, value)
-    return union
diff --git a/third_party/mojo/src/mojo/public/tools/NETWORK_SERVICE_VERSION b/third_party/mojo/src/mojo/public/tools/NETWORK_SERVICE_VERSION
index 09436b5..7b21d79 100644
--- a/third_party/mojo/src/mojo/public/tools/NETWORK_SERVICE_VERSION
+++ b/third_party/mojo/src/mojo/public/tools/NETWORK_SERVICE_VERSION
@@ -1 +1 @@
-f4116cee892c698374ee7ae9ad8e6cea69741122
+36d008970120c7bce0e7cb0a6543fd0b653dad88
\ No newline at end of file
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/enum_declaration.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/enum_declaration.tmpl
index d212e8b..86c85d7d 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/enum_declaration.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/enum_declaration.tmpl
@@ -1,4 +1,4 @@
-enum {{enum.name}} : int32_t {
+enum {{enum.name}} {
 {%- for field in enum.fields %}
 {%-    if field.value %}
   {{enum.name|to_all_caps}}_{{field.name}} = {{field.value|expression_to_text}},
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl
index 56a7047..d96fb60 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/module.h.tmpl
@@ -8,10 +8,9 @@
 #ifndef {{header_guard}}
 #define {{header_guard}}
 
-#include <stdint.h>
-
 #include "mojo/public/cpp/bindings/array.h"
 #include "mojo/public/cpp/bindings/callback.h"
+#include "mojo/public/cpp/bindings/interface_impl.h"
 #include "mojo/public/cpp/bindings/interface_ptr.h"
 #include "mojo/public/cpp/bindings/interface_request.h"
 #include "mojo/public/cpp/bindings/lib/control_message_handler.h"
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/java_templates/interface_definition.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/java_templates/interface_definition.tmpl
index 320abeb..39c17cc 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/java_templates/interface_definition.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/java_templates/interface_definition.tmpl
@@ -36,14 +36,14 @@ interface {{method|interface_response_name}} extends org.chromium.mojo.bindings.
 {%-   endif -%}
 {%- endmacro -%}
 
-{%- macro flags_for_method(method, is_request) -%}
-{{flags(method.response_parameters != None, is_request)}}
+{%- macro flags_for_method(method, is_parameter) -%}
+{{flags(method.response_parameters, is_parameter)}}
 {%- endmacro -%}
 
-{%- macro flags(use_response_flag, is_request) -%}
-{%-  if not use_response_flag -%}
+{%- macro flags(has_response_parameters, is_parameter) -%}
+{%-  if not has_response_parameters -%}
 org.chromium.mojo.bindings.MessageHeader.NO_FLAG
-{%-   elif is_request: -%}
+{%-   elif is_parameter: -%}
 org.chromium.mojo.bindings.MessageHeader.MESSAGE_EXPECTS_RESPONSE_FLAG
 {%-   else -%}
 org.chromium.mojo.bindings.MessageHeader.MESSAGE_IS_RESPONSE_FLAG
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_dart_generator.py b/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_dart_generator.py
index c324c9c..87c16ef 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_dart_generator.py
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_dart_generator.py
@@ -9,7 +9,6 @@ import re
 import shutil
 import sys
 
-import mojom.fileutil as fileutil
 import mojom.generate.constant_resolver as resolver
 import mojom.generate.generator as generator
 import mojom.generate.module as mojom
@@ -422,25 +421,20 @@ class Generator(generator.Generator):
   def GenerateFiles(self, args):
     elements = self.module.namespace.split('.')
     elements.append("%s.dart" % self.module.name)
-
-    lib_module = self.GenerateLibModule(args)
-    pkg_path = os.path.join("dart-pkg", "mojom/lib", *elements)
-    self.Write(lib_module, pkg_path)
-
-    gen_path = os.path.join("dart-gen", "mojom/lib", *elements)
-    full_gen_path = os.path.join(self.output_dir, gen_path)
-    self.Write(lib_module, gen_path)
-
+    path = os.path.join("dart-pkg", "mojom/lib", *elements)
+    self.Write(self.GenerateLibModule(args), path)
+    path = os.path.join("dart-gen", "mojom/lib", *elements)
+    self.Write(self.GenerateLibModule(args), path)
     link = self.MatchMojomFilePath("%s.dart" % self.module.name)
-    full_link_path = os.path.join(self.output_dir, link)
-    if os.path.exists(full_link_path):
-      os.unlink(full_link_path)
-    fileutil.EnsureDirectoryExists(os.path.dirname(full_link_path))
+    if os.path.exists(os.path.join(self.output_dir, link)):
+      os.unlink(os.path.join(self.output_dir, link))
     try:
       if sys.platform == "win32":
-        shutil.copy(full_gen_path, full_link_path)
+        shutil.copy(os.path.join(self.output_dir, path),
+                    os.path.join(self.output_dir, link))
       else:
-        os.symlink(full_gen_path, full_link_path)
+        os.symlink(os.path.join(self.output_dir, path),
+                   os.path.join(self.output_dir, link))
     except OSError as e:
       # Errno 17 is file already exists. If the link fails because file already
       # exists assume another instance of this script tried to create the same
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_python_generator.py b/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_python_generator.py
index a12f5e1..1f726b6 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_python_generator.py
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_python_generator.py
@@ -146,13 +146,7 @@ def GetFieldType(kind, field=None):
       arguments.append('nullable=True')
     return '_descriptor.MapType(%s)' % ', '.join(arguments)
 
-  if mojom.IsUnionKind(kind):
-    arguments = [ 'lambda: %s' % GetFullyQualifiedName(kind) ]
-    if mojom.IsNullableKind(kind):
-      arguments.append('nullable=True')
-    return '_descriptor.UnionType(%s)' % ', '.join(arguments)
-
-  if mojom.IsStructKind(kind):
+  if mojom.IsStructKind(kind) or mojom.IsUnionKind(kind):
     arguments = [ 'lambda: %s' % GetFullyQualifiedName(kind) ]
     if mojom.IsNullableKind(kind):
       arguments.append('nullable=True')
@@ -175,14 +169,15 @@ def GetFieldType(kind, field=None):
 
   return _kind_to_type[kind]
 
-def GetFieldDescriptor(field, index, min_version):
+def GetFieldDescriptor(packed_field):
+  field = packed_field.field
   class_name = 'SingleFieldGroup'
   if field.kind == mojom.BOOL:
     class_name = 'FieldDescriptor'
   arguments = [ '%r' % GetNameForElement(field) ]
   arguments.append(GetFieldType(field.kind, field))
-  arguments.append(str(index))
-  arguments.append(str(min_version))
+  arguments.append(str(packed_field.index))
+  arguments.append(str(packed_field.min_version))
   if field.default:
     if mojom.IsStructKind(field.kind):
       arguments.append('default_value=True')
@@ -190,19 +185,12 @@ def GetFieldDescriptor(field, index, min_version):
       arguments.append('default_value=%s' % ExpressionToText(field.default))
   return '_descriptor.%s(%s)' % (class_name, ', '.join(arguments))
 
-def GetStructFieldDescriptor(packed_field):
-  return GetFieldDescriptor(
-      packed_field.field, packed_field.index, packed_field.min_version)
-
-def GetUnionFieldDescriptor(field):
-  return GetFieldDescriptor(field, field.ordinal, 0)
-
 def GetFieldGroup(byte):
   if byte.packed_fields[0].field.kind == mojom.BOOL:
-    descriptors = map(GetStructFieldDescriptor, byte.packed_fields)
+    descriptors = map(GetFieldDescriptor, byte.packed_fields)
     return '_descriptor.BooleanGroup([%s])' % ', '.join(descriptors)
   assert len(byte.packed_fields) == 1
-  return GetStructFieldDescriptor(byte.packed_fields[0])
+  return GetFieldDescriptor(byte.packed_fields[0])
 
 def MojomToPythonImport(mojom):
   return mojom.replace('.mojom', '_mojom')
@@ -212,7 +200,6 @@ class Generator(generator.Generator):
   python_filters = {
     'expression_to_text': ExpressionToText,
     'field_group': GetFieldGroup,
-    'union_field_descriptor': GetUnionFieldDescriptor,
     'fully_qualified_name': GetFullyQualifiedName,
     'name': GetNameForElement,
   }
@@ -226,7 +213,6 @@ class Generator(generator.Generator):
       'module': resolver.ResolveConstants(self.module, ExpressionToText),
       'namespace': self.module.namespace,
       'structs': self.GetStructs(),
-      'unions': self.GetUnions(),
     }
 
   def GenerateFiles(self, args):
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/python_templates/module.py.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/python_templates/module.py.tmpl
index 9d57600..2a22932 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/python_templates/module.py.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/python_templates/module.py.tmpl
@@ -1,6 +1,5 @@
 {% from "module_macros.tmpl" import enum_values %}
 {% from "module_macros.tmpl" import struct_descriptor %}
-{% from "module_macros.tmpl" import union_descriptor %}
 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
@@ -35,13 +34,6 @@ class {{struct|name}}(object):
   __metaclass__ = _reflection.MojoStructType
   DESCRIPTOR = {{struct_descriptor(struct)|indent(2)}}
 {% endfor %}
-{% for union in unions %}
-
-class {{union|name}}(object):
-  __metaclass__ = _reflection.MojoUnionType
-  DESCRIPTOR = {{union_descriptor(union)|indent(2)}}
-{% endfor %}
-
 {% for interface in interfaces %}
 
 class {{interface|name}}(object):
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/python_templates/module_macros.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/python_templates/module_macros.tmpl
index c979f59..21c70db 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/python_templates/module_macros.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/python_templates/module_macros.tmpl
@@ -37,13 +37,3 @@
 {% endif %}
 }
 {%- endmacro -%}
-
-{%- macro union_descriptor(union) -%}
-{
-  'fields': [
-{% for field in union.fields %}
-    {{field|union_field_descriptor}},
-{% endfor %}
-  ],
- }
-{%- endmacro -%}
diff --git a/third_party/mojo/src/mojo/public/tools/dart_pkg.py b/third_party/mojo/src/mojo/public/tools/dart_pkg.py
index 86ae5d5..d0f0d6eb 100755
--- a/third_party/mojo/src/mojo/public/tools/dart_pkg.py
+++ b/third_party/mojo/src/mojo/public/tools/dart_pkg.py
@@ -8,7 +8,6 @@
 
 import argparse
 import errno
-import json
 import os
 import shutil
 import sys
@@ -48,9 +47,8 @@ def mojom_filter(path):
 
 
 def ensure_dir_exists(path):
-    abspath = os.path.abspath(path)
-    if not os.path.exists(abspath):
-        os.makedirs(abspath)
+    if not os.path.exists(path):
+        os.makedirs(path)
 
 
 def has_pubspec_yaml(paths):
@@ -107,13 +105,6 @@ def copy_or_link(from_root, to_root, filter_func=None):
         copy(from_root, to_root, filter_func)
 
 
-def remove_if_exists(path):
-    try:
-        os.remove(path)
-    except OSError as e:
-        if e.errno != errno.ENOENT:
-            raise
-
 def list_files(from_root, filter_func=None):
     file_list = []
     for root, dirs, files in os.walk(from_root):
@@ -196,39 +187,13 @@ def main():
                         help='Directory containing .dart sources',
                         nargs='*',
                         default=[])
-    parser.add_argument('--sdk-ext-files',
-                        metavar='sdk_ext_files',
-                        help='List of .dart files that are part of of sdk_ext.',
-                        nargs='*',
-                        default=[])
-    parser.add_argument('--sdk-ext-mappings',
-                        metavar='sdk_ext_mappings',
-                        help='Mappings for SDK extension libraries.',
-                        nargs='*',
-                        default=[])
     args = parser.parse_args()
 
     # We must have a pubspec.yaml.
     assert has_pubspec_yaml(args.package_sources)
 
-    target_dir = os.path.join(args.pkg_directory, args.package_name)
-    lib_path = os.path.join(target_dir, "lib")
-
-    mappings = {}
-    for mapping in args.sdk_ext_mappings:
-        library, path = mapping.split(',', 1)
-        mappings[library] = '../sdk_ext/%s' % path
-
-    sdkext_path = os.path.join(lib_path, '_sdkext')
-    if mappings:
-        ensure_dir_exists(lib_path)
-        with open(sdkext_path, 'w') as stream:
-            json.dump(mappings, stream, sort_keys=True,
-                      indent=2, separators=(',', ': '))
-    else:
-        remove_if_exists(sdkext_path)
-
     # Copy or symlink package sources into pkg directory.
+    target_dir = os.path.join(args.pkg_directory, args.package_name)
     common_source_prefix = os.path.commonprefix(args.package_sources)
     for source in args.package_sources:
         relative_source = os.path.relpath(source, common_source_prefix)
@@ -244,12 +209,8 @@ def main():
             relative_source = os.path.relpath(source, common_prefix)
             target = os.path.join(sdk_ext_dir, relative_source)
             copy_or_link(source, target)
-    for source in args.sdk_ext_files:
-        common_prefix = os.path.commonprefix(args.sdk_ext_files)
-        relative_source = os.path.relpath(source, common_prefix)
-        target = os.path.join(sdk_ext_dir, relative_source)
-        copy_or_link(source, target)
 
+    lib_path = os.path.join(target_dir, "lib")
     lib_mojom_path = os.path.join(lib_path, "mojom")
 
     # Copy generated mojom.dart files.