Revert of Fix the handling of user gestures for external protocol handler dialogs. (https://codereview.chromium.org/131783012/)

Reason for revert:
Looks like this caused a failure on the build bots.  

http://build.chromium.org/p/chromium.linux/builders/Linux%20Clang%20%28dbg%29/builds/57837

FAILED: /b/build/goma/gomacc ../../third_party/llvm-build/Release+Asserts/bin/clang++ -MMD -MF obj/apps/shell/browser/app_shell_lib.shell_extensions_browser_client.o.d -DV8_DEPRECATION_WARNINGS -DBLINK_SCALE_FILTERS_AT_RECORD_TIME -D_FILE_OFFSET_BITS=64 -DCHROMIUM_BUILD -DCOMPONENT_BUILD -DTOOLKIT_VIEWS=1 -DUI_COMPOSITOR_IMAGE_TRANSPORT -DUSE_AURA=1 -DUSE_CAIRO=1 -DUSE_GLIB=1 -DUSE_DEFAULT_RENDER_THEME=1 -DUSE_LIBJPEG_TURBO=1 -DUSE_MOJO=1 -DUSE_X11=1 -DUSE_CLIPBOARD_AURAX11=1 -DENABLE_ONE_CLICK_SIGNIN -DUSE_XI2_MT=2 -DENABLE_REMOTING=1 -DENABLE_WEBRTC=1 -DENABLE_PEPPER_CDMS -DENABLE_CONFIGURATION_POLICY -DENABLE_INPUT_SPEECH -DENABLE_NOTIFICATIONS -DUSE_UDEV -DENABLE_EGLIMAGE=1 -DENABLE_TASK_MANAGER=1 -DENABLE_EXTENSIONS=1 -DENABLE_PLUGIN_INSTALLATION=1 -DENABLE_PLUGINS=1 -DENABLE_SESSION_SERVICE=1 -DENABLE_THEMES=1 -DENABLE_AUTOFILL_DIALOG=1 -DENABLE_BACKGROUND=1 -DENABLE_AUTOMATION=1 -DENABLE_GOOGLE_NOW=1 -DCLD_VERSION=2 -DENABLE_FULL_PRINTING=1 -DENABLE_PRINTING=1 -DENABLE_SPELLCHECK=1 -DENABLE_CAPTIVE_PORTAL_DETECTION=1 -DENABLE_APP_LIST=1 -DENABLE_SETTINGS_APP=1 -DENABLE_MANAGED_USERS=1 -DENABLE_MDNS=1 -DENABLE_SERVICE_DISCOVERY=1 -DGL_GLEXT_PROTOTYPES -DGTEST_HAS_POSIX_RE=0 -DLIBPEERCONNECTION_LIB=1 -DU_USING_ICU_NAMESPACE=0 -DV8_SHARED -DUSING_V8_SHARED -DCHROME_PNG_WRITE_SUPPORT -DPNG_USER_CONFIG -DSKIA_DLL -DGR_GL_IGNORE_ES3_MSAA=0 -DSK_ENABLE_INST_COUNT=0 -DSK_SUPPORT_GPU=1 '-DGR_GL_CUSTOM_SETUP_HEADER="GrGLConfig_chrome.h"' -DSK_ENABLE_LEGACY_API_ALIASING=1 -DSK_ATTR_DEPRECATED=SK_NOTHING_ARG1 -DSK_SUPPORT_LEGACY_LAYERRASTERIZER_API=1 -DSK_WILL_NEVER_DRAW_PERSPECTIVE_TEXT -DSK_SUPPORT_LEGACY_PUBLICEFFECTCONSTRUCTORS=1 -DSK_SUPPORT_LEGACY_GETCLIPTYPE -DSK_SUPPORT_LEGACY_GETTOTALCLIP -DSK_SUPPORT_LEGACY_GETTOPDEVICE -DSK_USE_POSIX_THREADS -DSK_DEFERRED_CANVAS_USES_FACTORIES=1 -DUSE_NSS=1 -D__STDC_CONSTANT_MACROS -D__STDC_FORMAT_MACROS -DDYNAMIC_ANNOTATIONS_ENABLED=1 -DWTF_USE_DYNAMIC_ANNOTATIONS=1 -D_DEBUG -D_GLIBCXX_DEBUG=1 -I../.. -I../../third_party/khronos -I../../gpu -I../../skia/config -I../../third_party/WebKit/Source -Igen -I../../third_party/WebKit -I../../third_party/icu/source/common -I../../third_party/npapi -I../../third_party/npapi/bindings -I../../v8/include -I../../third_party/libpng -I../../third_party/zlib -I../../third_party/libwebp -I../../third_party/ots/include -I../../third_party/qcms/src -I../../third_party/iccjpeg -I../../third_party/libjpeg_turbo -Igen/policy -Igen/protoc_out -I../../third_party/WebKit -I../../third_party/skia/src/core -I../../third_party/skia/include/core -I../../third_party/skia/include/effects -I../../third_party/skia/include/pdf -I../../third_party/skia/include/gpu -I../../third_party/skia/include/lazy -I../../third_party/skia/include/pathops -I../../third_party/skia/include/pipe -I../../third_party/skia/include/ports -I../../third_party/skia/include/utils -I../../skia/ext -fstack-protector --param=ssp-buffer-size=4 -Werror -pthread -fno-exceptions -fno-strict-aliasing -Wall -Wno-unused-parameter -Wno-missing-field-initializers -fvisibility=hidden -pipe -fPIC -Wheader-hygiene -Wno-char-subscripts -Wno-unneeded-internal-declaration -Wno-covered-switch-default -Wstring-conversion -Wno-c++11-narrowing -Wno-reserved-user-defined-literal -Wno-deprecated-register -Wno-absolute-value -Xclang -load -Xclang /b/build/slave/Linux_Clang__dbg_/build/src/tools/clang/scripts/../../../third_party/llvm-build/Release+Asserts/lib/libFindBadConstructs.so -Xclang -add-plugin -Xclang find-bad-constructs -fcolor-diagnostics -pthread -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -I/usr/include/gtk-2.0 -I/usr/lib/x86_64-linux-gnu/gtk-2.0/include -I/usr/include/atk-1.0 -I/usr/include/cairo -I/usr/include/gdk-pixbuf-2.0 -I/usr/include/pango-1.0 -I/usr/include/gio-unix-2.0/ -I/usr/include/pixman-1 -I/usr/include/freetype2 -I/usr/include/libpng12 -pthread -I/usr/include/glib-2.0 -I/usr/lib/x86_64-linux-gnu/glib-2.0/include -m64 -march=x86-64 -O0 -g -funwind-tables -fno-rtti -fno-threadsafe-statics -fvisibility-inlines-hidden -Wsign-compare -std=gnu++11  -c ../../apps/shell/browser/shell_extensions_browser_client.cc -o obj/apps/shell/browser/app_shell_lib.shell_extensions_browser_client.o
In file included from ../../apps/shell/browser/shell_extensions_browser_client.cc:5:
../../apps/shell/browser/shell_extensions_browser_client.h:54:16:error: 'PermitExternalProtocolHandler' marked 'override' but does not override any member functions
  virtual void PermitExternalProtocolHandler() OVERRIDE;


Original issue's description:
> Fix the handling of user gestures for external protocol handler dialogs.
> 
> - Remove browser state from external protocol handler.
> - Use gesture with a timeout.
> 
> BUG=173557
> 
> Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=261014

TBR=jyasskin@chromium.org,kalman@chromium.org,mmenke@chromium.org,joi@chromium.org,pkasting@chromium.org,jochen@chromium.org,boliu@chromium.org,meacer@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=173557

Review URL: https://codereview.chromium.org/221283006

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@261022 0039d316-1c4b-4281-b951-d872f2087c98

23 files changed, 138 insertions, 73 deletions

diff --git a/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc b/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc
index 05eb520..00b6e60 100644
--- a/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc
+++ b/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.cc
@@ -298,11 +298,9 @@ content::ResourceDispatcherHostLoginDelegate*
   return new AwLoginDelegate(auth_info, request);
 }
 
-bool AwResourceDispatcherHostDelegate::HandleExternalProtocol(
-    const GURL& url,
-    int child_id,
-    int route_id,
-    bool initiated_by_user_gesture) {
+bool AwResourceDispatcherHostDelegate::HandleExternalProtocol(const GURL& url,
+                                                              int child_id,
+                                                              int route_id) {
   // The AwURLRequestJobFactory implementation should ensure this method never
   // gets called.
   NOTREACHED();
diff --git a/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.h b/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.h
index 8702b09..e584c40 100644
--- a/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.h
+++ b/android_webview/browser/renderer_host/aw_resource_dispatcher_host_delegate.h
@@ -51,8 +51,7 @@ class AwResourceDispatcherHostDelegate
       net::URLRequest* request) OVERRIDE;
   virtual bool HandleExternalProtocol(const GURL& url,
                                       int child_id,
-                                      int route_id,
-                                      bool initiated_by_user_gesture) OVERRIDE;
+                                      int route_id) OVERRIDE;
   virtual void OnResponseStarted(
       net::URLRequest* request,
       content::ResourceContext* resource_context,
diff --git a/chrome/browser/autocomplete/autocomplete_input.cc b/chrome/browser/autocomplete/autocomplete_input.cc
index 4672f0c..ea42851 100644
--- a/chrome/browser/autocomplete/autocomplete_input.cc
+++ b/chrome/browser/autocomplete/autocomplete_input.cc
@@ -198,12 +198,9 @@ AutocompleteInput::Type AutocompleteInput::Parse(
     // handlable schemes (e.g. "javascript") may be treated as "blocked" by the
     // external protocol handler because we don't want pages to open them, but
     // users still can.
-    // Note that the protocol handler needs to be informed that omnibox input
-    // should always be considered "user gesture-triggered", lest it always
-    // return BLOCK.
     ExternalProtocolHandler::BlockState block_state =
         ExternalProtocolHandler::GetBlockState(
-            base::UTF16ToUTF8(parsed_scheme), true);
+            base::UTF16ToUTF8(parsed_scheme));
     switch (block_state) {
       case ExternalProtocolHandler::DONT_BLOCK:
         return return_value_for_non_http_url;
diff --git a/chrome/browser/extensions/active_tab_permission_granter.cc b/chrome/browser/extensions/active_tab_permission_granter.cc
index 756007e..ecedd34 100644
--- a/chrome/browser/extensions/active_tab_permission_granter.cc
+++ b/chrome/browser/extensions/active_tab_permission_granter.cc
@@ -37,9 +37,6 @@ ActiveTabPermissionGranter::ActiveTabPermissionGranter(
 ActiveTabPermissionGranter::~ActiveTabPermissionGranter() {}
 
 void ActiveTabPermissionGranter::GrantIfRequested(const Extension* extension) {
-  // Active tab grant request implies there was a user gesture.
-  web_contents()->UserGestureDone();
-
   if (granted_extensions_.Contains(extension->id()))
     return;
 
diff --git a/chrome/browser/extensions/chrome_extensions_browser_client.cc b/chrome/browser/extensions/chrome_extensions_browser_client.cc
index a8582a2..67d76bd 100644
--- a/chrome/browser/extensions/chrome_extensions_browser_client.cc
+++ b/chrome/browser/extensions/chrome_extensions_browser_client.cc
@@ -183,6 +183,10 @@ bool ChromeExtensionsBrowserClient::DidVersionUpdate(
   return last_version.IsOlderThan(current_version);
 }
 
+void ChromeExtensionsBrowserClient::PermitExternalProtocolHandler() {
+  ExternalProtocolHandler::PermitLaunchUrl();
+}
+
 scoped_ptr<AppSorting> ChromeExtensionsBrowserClient::CreateAppSorting() {
   return scoped_ptr<AppSorting>(new ChromeAppSorting());
 }
diff --git a/chrome/browser/extensions/chrome_extensions_browser_client.h b/chrome/browser/extensions/chrome_extensions_browser_client.h
index f7c7752..dd2d469 100644
--- a/chrome/browser/extensions/chrome_extensions_browser_client.h
+++ b/chrome/browser/extensions/chrome_extensions_browser_client.h
@@ -64,6 +64,7 @@ class ChromeExtensionsBrowserClient : public ExtensionsBrowserClient {
   virtual scoped_ptr<ExtensionHostDelegate> CreateExtensionHostDelegate()
       OVERRIDE;
   virtual bool DidVersionUpdate(content::BrowserContext* context) OVERRIDE;
+  virtual void PermitExternalProtocolHandler() OVERRIDE;
   virtual scoped_ptr<AppSorting> CreateAppSorting() OVERRIDE;
   virtual bool IsRunningInForcedAppMode() OVERRIDE;
   virtual ApiActivityMonitor* GetApiActivityMonitor(
diff --git a/chrome/browser/external_protocol/external_protocol_handler.cc b/chrome/browser/external_protocol/external_protocol_handler.cc
index 78334d9..b414261 100644
--- a/chrome/browser/external_protocol/external_protocol_handler.cc
+++ b/chrome/browser/external_protocol/external_protocol_handler.cc
@@ -27,6 +27,11 @@
 
 using content::BrowserThread;
 
+// Whether we accept requests for launching external protocols. This is set to
+// false every time an external protocol is requested, and set back to true on
+// each user gesture. This variable should only be accessed from the UI thread.
+static bool g_accept_requests = true;
+
 namespace {
 
 // Functions enabling unit testing. Using a NULL delegate will use the default
@@ -44,13 +49,11 @@ ShellIntegration::DefaultProtocolClientWorker* CreateShellWorker(
 
 ExternalProtocolHandler::BlockState GetBlockStateWithDelegate(
     const std::string& scheme,
-    ExternalProtocolHandler::Delegate* delegate,
-    bool initiated_by_user_gesture) {
+    ExternalProtocolHandler::Delegate* delegate) {
   if (!delegate)
-    return ExternalProtocolHandler::GetBlockState(scheme,
-                                                  initiated_by_user_gesture);
+    return ExternalProtocolHandler::GetBlockState(scheme);
 
-  return delegate->GetBlockState(scheme, initiated_by_user_gesture);
+  return delegate->GetBlockState(scheme);
 }
 
 void RunExternalProtocolDialogWithDelegate(
@@ -200,9 +203,9 @@ void ExternalProtocolHandler::PrepopulateDictionary(
 
 // static
 ExternalProtocolHandler::BlockState ExternalProtocolHandler::GetBlockState(
-    const std::string& scheme,
-    bool initiated_by_user_gesture) {
-  if (!initiated_by_user_gesture)
+    const std::string& scheme) {
+  // If we are being carpet bombed, block the request.
+  if (!g_accept_requests)
     return BLOCK;
 
   if (scheme.length() == 1) {
@@ -249,12 +252,10 @@ void ExternalProtocolHandler::SetBlockState(const std::string& scheme,
 }
 
 // static
-void ExternalProtocolHandler::LaunchUrlWithDelegate(
-    const GURL& url,
-    int render_process_host_id,
-    int tab_contents_id,
-    Delegate* delegate,
-    bool initiated_by_user_gesture) {
+void ExternalProtocolHandler::LaunchUrlWithDelegate(const GURL& url,
+                                                    int render_process_host_id,
+                                                    int tab_contents_id,
+                                                    Delegate* delegate) {
   DCHECK(base::MessageLoopForUI::IsCurrent());
 
   // Escape the input scheme to be sure that the command does not
@@ -262,14 +263,15 @@ void ExternalProtocolHandler::LaunchUrlWithDelegate(
   std::string escaped_url_string = net::EscapeExternalHandlerValue(url.spec());
   GURL escaped_url(escaped_url_string);
   BlockState block_state = GetBlockStateWithDelegate(escaped_url.scheme(),
-                                                     delegate,
-                                                     initiated_by_user_gesture);
+                                                     delegate);
   if (block_state == BLOCK) {
     if (delegate)
       delegate->BlockRequest();
     return;
   }
 
+  g_accept_requests = false;
+
   // The worker creates tasks with references to itself and puts them into
   // message loops. When no tasks are left it will delete the observer and
   // eventually be deleted itself.
@@ -306,3 +308,9 @@ void ExternalProtocolHandler::LaunchUrlWithoutSecurityCheck(
 void ExternalProtocolHandler::RegisterPrefs(PrefRegistrySimple* registry) {
   registry->RegisterDictionaryPref(prefs::kExcludedSchemes);
 }
+
+// static
+void ExternalProtocolHandler::PermitLaunchUrl() {
+  DCHECK(base::MessageLoopForUI::IsCurrent());
+  g_accept_requests = true;
+}
diff --git a/chrome/browser/external_protocol/external_protocol_handler.h b/chrome/browser/external_protocol/external_protocol_handler.h
index 6780d10..7c934c5 100644
--- a/chrome/browser/external_protocol/external_protocol_handler.h
+++ b/chrome/browser/external_protocol/external_protocol_handler.h
@@ -30,8 +30,7 @@ class ExternalProtocolHandler {
     virtual ShellIntegration::DefaultProtocolClientWorker* CreateShellWorker(
         ShellIntegration::DefaultWebClientObserver* observer,
         const std::string& protocol) = 0;
-    virtual BlockState GetBlockState(const std::string& scheme,
-                                     bool initiated_by_user_gesture) = 0;
+    virtual BlockState GetBlockState(const std::string& scheme) = 0;
     virtual void BlockRequest() = 0;
     virtual void RunExternalProtocolDialog(const GURL& url,
                                            int render_process_host_id,
@@ -42,17 +41,27 @@ class ExternalProtocolHandler {
   };
 
   // Returns whether we should block a given scheme.
-  static BlockState GetBlockState(const std::string& scheme,
-                                  bool initiated_by_user_gesture);
+  static BlockState GetBlockState(const std::string& scheme);
 
   // Sets whether we should block a given scheme.
   static void SetBlockState(const std::string& scheme, BlockState state);
 
+  // Checks to see if the protocol is allowed, if it is whitelisted,
+  // the application associated with the protocol is launched on the io thread,
+  // if it is blacklisted, returns silently. Otherwise, an
+  // ExternalProtocolDialog is created asking the user. If the user accepts,
+  // LaunchUrlWithoutSecurityCheck is called on the io thread and the
+  // application is launched.
+  // Must run on the UI thread.
+  static void LaunchUrl(const GURL& url, int render_process_host_id,
+                        int tab_contents_id) {
+      LaunchUrlWithDelegate(url, render_process_host_id, tab_contents_id, NULL);
+  }
+
   // Version of LaunchUrl allowing use of a delegate to facilitate unit
   // testing.
   static void LaunchUrlWithDelegate(const GURL& url, int render_process_host_id,
-                                    int tab_contents_id, Delegate* delegate,
-                                    bool initiated_by_user_gesture);
+                                    int tab_contents_id, Delegate* delegate);
 
   // Creates and runs a External Protocol dialog box.
   // |url| - The url of the request.
@@ -87,8 +96,11 @@ class ExternalProtocolHandler {
   // preferences for them do not already exist.
   static void PrepopulateDictionary(base::DictionaryValue* win_pref);
 
- private:
-  DISALLOW_COPY_AND_ASSIGN(ExternalProtocolHandler);
+  // Allows LaunchUrl to proceed with launching an external protocol handler.
+  // This is typically triggered by a user gesture, but is also called for
+  // each extension API function. Note that each call to LaunchUrl resets
+  // the state to false (not allowed).
+  static void PermitLaunchUrl();
 };
 
 #endif  // CHROME_BROWSER_EXTERNAL_PROTOCOL_EXTERNAL_PROTOCOL_HANDLER_H_
diff --git a/chrome/browser/external_protocol/external_protocol_handler_unittest.cc b/chrome/browser/external_protocol/external_protocol_handler_unittest.cc
index 0b27465..57a6db6 100644
--- a/chrome/browser/external_protocol/external_protocol_handler_unittest.cc
+++ b/chrome/browser/external_protocol/external_protocol_handler_unittest.cc
@@ -51,8 +51,7 @@ class FakeExternalProtocolHandlerDelegate
   }
 
   virtual ExternalProtocolHandler::BlockState GetBlockState(
-      const std::string& scheme,
-      bool initiated_by_user_gesture) OVERRIDE { return block_state_; }
+      const std::string& scheme) OVERRIDE { return block_state_; }
 
   virtual void BlockRequest() OVERRIDE {
     ASSERT_TRUE(block_state_ == ExternalProtocolHandler::BLOCK ||
@@ -108,6 +107,11 @@ class ExternalProtocolHandlerTest : public testing::Test {
     file_thread_.Start();
   }
 
+  virtual void TearDown() {
+    // Ensure that g_accept_requests gets set back to true after test execution.
+    ExternalProtocolHandler::PermitLaunchUrl();
+  }
+
   void DoTest(ExternalProtocolHandler::BlockState block_state,
               ShellIntegration::DefaultWebClientState os_state,
               bool should_prompt, bool should_launch, bool should_block) {
@@ -118,7 +122,7 @@ class ExternalProtocolHandlerTest : public testing::Test {
 
     delegate_.set_block_state(block_state);
     delegate_.set_os_state(os_state);
-    ExternalProtocolHandler::LaunchUrlWithDelegate(url, 0, 0, &delegate_, true);
+    ExternalProtocolHandler::LaunchUrlWithDelegate(url, 0, 0, &delegate_);
     if (block_state != ExternalProtocolHandler::BLOCK)
       base::MessageLoop::current()->Run();
 
diff --git a/chrome/browser/external_protocol/external_protocol_observer.cc b/chrome/browser/external_protocol/external_protocol_observer.cc
new file mode 100644
index 0000000..8f69517
--- /dev/null
+++ b/chrome/browser/external_protocol/external_protocol_observer.cc
@@ -0,0 +1,22 @@
+// 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 "chrome/browser/external_protocol/external_protocol_observer.h"
+
+#include "chrome/browser/external_protocol/external_protocol_handler.h"
+
+using content::WebContents;
+
+DEFINE_WEB_CONTENTS_USER_DATA_KEY(ExternalProtocolObserver);
+
+ExternalProtocolObserver::ExternalProtocolObserver(WebContents* web_contents)
+    : content::WebContentsObserver(web_contents) {
+}
+
+ExternalProtocolObserver::~ExternalProtocolObserver() {
+}
+
+void ExternalProtocolObserver::DidGetUserGesture() {
+  ExternalProtocolHandler::PermitLaunchUrl();
+}
diff --git a/chrome/browser/external_protocol/external_protocol_observer.h b/chrome/browser/external_protocol/external_protocol_observer.h
new file mode 100644
index 0000000..8249c3d
--- /dev/null
+++ b/chrome/browser/external_protocol/external_protocol_observer.h
@@ -0,0 +1,29 @@
+// 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 CHROME_BROWSER_EXTERNAL_PROTOCOL_EXTERNAL_PROTOCOL_OBSERVER_H_
+#define CHROME_BROWSER_EXTERNAL_PROTOCOL_EXTERNAL_PROTOCOL_OBSERVER_H_
+
+#include "content/public/browser/web_contents_observer.h"
+#include "content/public/browser/web_contents_user_data.h"
+
+// ExternalProtocolObserver is responsible for handling messages from
+// WebContents relating to external protocols.
+class ExternalProtocolObserver
+    : public content::WebContentsObserver,
+      public content::WebContentsUserData<ExternalProtocolObserver> {
+ public:
+  virtual ~ExternalProtocolObserver();
+
+  // content::WebContentsObserver overrides.
+  virtual void DidGetUserGesture() OVERRIDE;
+
+ private:
+  explicit ExternalProtocolObserver(content::WebContents* web_contents);
+  friend class content::WebContentsUserData<ExternalProtocolObserver>;
+
+  DISALLOW_COPY_AND_ASSIGN(ExternalProtocolObserver);
+};
+
+#endif  // CHROME_BROWSER_EXTERNAL_PROTOCOL_EXTERNAL_PROTOCOL_OBSERVER_H_
diff --git a/chrome/browser/prerender/prerender_browsertest.cc b/chrome/browser/prerender/prerender_browsertest.cc
index 68841b8..af8e09e 100644
--- a/chrome/browser/prerender/prerender_browsertest.cc
+++ b/chrome/browser/prerender/prerender_browsertest.cc
@@ -972,8 +972,7 @@ class NeverRunsExternalProtocolHandlerDelegate
     return NULL;
   }
   virtual ExternalProtocolHandler::BlockState GetBlockState(
-      const std::string& scheme,
-      bool initiated_by_user_gesture) OVERRIDE {
+      const std::string& scheme) OVERRIDE {
     // Block everything and fail the test.
     ADD_FAILURE();
     return ExternalProtocolHandler::BLOCK;
diff --git a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
index 8fe2144..268e374 100644
--- a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
+++ b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.cc
@@ -198,8 +198,7 @@ void SendExecuteMimeTypeHandlerEvent(scoped_ptr<content::StreamHandle> stream,
       extension_id, web_contents, stream.Pass(), expected_content_size);
 }
 
-void LaunchURL(const GURL& url, int render_process_id, int render_view_id,
-               bool user_gesture) {
+void LaunchURL(const GURL& url, int render_process_id, int render_view_id) {
   // If there is no longer a WebContents, the request may have raced with tab
   // closing. Don't fire the external request. (It may have been a prerender.)
   content::WebContents* web_contents =
@@ -218,8 +217,7 @@ void LaunchURL(const GURL& url, int render_process_id, int render_view_id,
 
   ExternalProtocolHandler::LaunchUrlWithDelegate(
       url, render_process_id, render_view_id,
-      g_external_protocol_handler_delegate,
-      user_gesture);
+      g_external_protocol_handler_delegate);
 }
 #endif  // !defined(OS_ANDROID)
 
@@ -443,10 +441,7 @@ ResourceDispatcherHostLoginDelegate*
 }
 
 bool ChromeResourceDispatcherHostDelegate::HandleExternalProtocol(
-    const GURL& url,
-    int child_id,
-    int route_id,
-    bool initiated_by_user_gesture) {
+    const GURL& url, int child_id, int route_id) {
 #if defined(OS_ANDROID)
   // Android use a resource throttle to handle external as well as internal
   // protocols.
@@ -462,8 +457,7 @@ bool ChromeResourceDispatcherHostDelegate::HandleExternalProtocol(
 
   BrowserThread::PostTask(
       BrowserThread::UI, FROM_HERE,
-      base::Bind(&LaunchURL, url, child_id, route_id,
-                 initiated_by_user_gesture));
+      base::Bind(&LaunchURL, url, child_id, route_id));
   return true;
 #endif
 }
diff --git a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h
index b154b5b..8bcf06a 100644
--- a/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h
+++ b/chrome/browser/renderer_host/chrome_resource_dispatcher_host_delegate.h
@@ -65,8 +65,7 @@ class ChromeResourceDispatcherHostDelegate
       net::AuthChallengeInfo* auth_info, net::URLRequest* request) OVERRIDE;
   virtual bool HandleExternalProtocol(const GURL& url,
                                       int child_id,
-                                      int route_id,
-                                      bool initiated_by_user_gesture) OVERRIDE;
+                                      int route_id) OVERRIDE;
   virtual bool ShouldForceDownloadResource(
       const GURL& url, const std::string& mime_type) OVERRIDE;
   virtual bool ShouldInterceptResourceAsStream(
diff --git a/chrome/browser/ui/tab_helpers.cc b/chrome/browser/ui/tab_helpers.cc
index 45853cd..5fd4fef 100644
--- a/chrome/browser/ui/tab_helpers.cc
+++ b/chrome/browser/ui/tab_helpers.cc
@@ -40,6 +40,7 @@
 #else
 #include "chrome/browser/extensions/api/web_navigation/web_navigation_api.h"
 #include "chrome/browser/extensions/chrome_extension_web_contents_observer.h"
+#include "chrome/browser/external_protocol/external_protocol_observer.h"
 #include "chrome/browser/net/predictor_tab_helper.h"
 #include "chrome/browser/network_time/navigation_time_helper.h"
 #include "chrome/browser/plugins/plugin_observer.h"
@@ -151,6 +152,7 @@ void TabHelpers::AttachTabHelpers(WebContents* web_contents) {
   extensions::ChromeExtensionWebContentsObserver::CreateForWebContents(
       web_contents);
   extensions::WebNavigationTabObserver::CreateForWebContents(web_contents);
+  ExternalProtocolObserver::CreateForWebContents(web_contents);
   HungPluginTabHelper::CreateForWebContents(web_contents);
   ManagePasswordsBubbleUIController::CreateForWebContents(web_contents);
   NavigationTimeHelper::CreateForWebContents(web_contents);
diff --git a/chrome/chrome_browser.gypi b/chrome/chrome_browser.gypi
index 93f008a..0403a63 100644
--- a/chrome/chrome_browser.gypi
+++ b/chrome/chrome_browser.gypi
@@ -654,6 +654,8 @@
         'browser/extensions/token_cache/token_cache_service_factory.h',
         'browser/external_protocol/external_protocol_handler.cc',
         'browser/external_protocol/external_protocol_handler.h',
+        'browser/external_protocol/external_protocol_observer.cc',
+        'browser/external_protocol/external_protocol_observer.h',
         'browser/favicon/favicon_changed_details.cc',
         'browser/favicon/favicon_changed_details.h',
         'browser/favicon/favicon_handler.cc',
@@ -3334,6 +3336,7 @@
             'browser/download/download_shelf.cc',
             'browser/download/download_shelf_context_menu.cc',
             'browser/drive/drive_switches.cc',
+            'browser/external_protocol/external_protocol_observer.cc',
             'browser/feedback/proto/annotations.proto',
             'browser/feedback/proto/chrome.proto',
             'browser/feedback/proto/common.proto',
diff --git a/content/browser/loader/resource_dispatcher_host_impl.cc b/content/browser/loader/resource_dispatcher_host_impl.cc
index c5e067d..61fc35b 100644
--- a/content/browser/loader/resource_dispatcher_host_impl.cc
+++ b/content/browser/loader/resource_dispatcher_host_impl.cc
@@ -679,15 +679,8 @@ bool ResourceDispatcherHostImpl::HandleExternalProtocol(ResourceLoader* loader,
   if (job_factory->IsHandledURL(url))
     return false;
 
-  bool initiated_by_user_gesture =
-      (loader->request()->load_flags() & net::LOAD_MAYBE_USER_GESTURE) != 0;
-  bool handled = delegate_->HandleExternalProtocol(url, info->GetChildID(),
-                                                   info->GetRouteID(),
-                                                   initiated_by_user_gesture);
-  // Consume the user gesture if the external protocol dialog is shown.
-  if (handled)
-    last_user_gesture_time_ = base::TimeTicks();
-  return handled;
+  return delegate_->HandleExternalProtocol(url, info->GetChildID(),
+                                           info->GetRouteID());
 }
 
 void ResourceDispatcherHostImpl::DidStartRequest(ResourceLoader* loader) {
diff --git a/content/public/browser/resource_dispatcher_host_delegate.cc b/content/public/browser/resource_dispatcher_host_delegate.cc
index ccd358f..bf92b25 100644
--- a/content/public/browser/resource_dispatcher_host_delegate.cc
+++ b/content/public/browser/resource_dispatcher_host_delegate.cc
@@ -46,11 +46,9 @@ ResourceDispatcherHostLoginDelegate*
   return NULL;
 }
 
-bool ResourceDispatcherHostDelegate::HandleExternalProtocol(
-    const GURL& url,
-    int child_id,
-    int route_id,
-    bool initiated_by_user_gesture) {
+bool ResourceDispatcherHostDelegate::HandleExternalProtocol(const GURL& url,
+                                                            int child_id,
+                                                            int route_id) {
   return true;
 }
 
diff --git a/content/public/browser/resource_dispatcher_host_delegate.h b/content/public/browser/resource_dispatcher_host_delegate.h
index 598cffb..0d0eebc 100644
--- a/content/public/browser/resource_dispatcher_host_delegate.h
+++ b/content/public/browser/resource_dispatcher_host_delegate.h
@@ -84,12 +84,9 @@ class CONTENT_EXPORT ResourceDispatcherHostDelegate {
   // Launches the url for the given tab. Returns true if an attempt to handle
   // the url was made, e.g. by launching an app. Note that this does not
   // guarantee that the app successfully handled it.
-  // Some external protocol handlers only run in the context of a user gesture,
-  // so initiated_by_user_gesture should be passed accordingly.
   virtual bool HandleExternalProtocol(const GURL& url,
                                       int child_id,
-                                      int route_id,
-                                      bool initiated_by_user_gesture);
+                                      int route_id);
 
   // Returns true if we should force the given resource to be downloaded.
   // Otherwise, the content layer decides.
diff --git a/extensions/browser/extension_function_dispatcher.cc b/extensions/browser/extension_function_dispatcher.cc
index d6420e3..5e0cffe 100644
--- a/extensions/browser/extension_function_dispatcher.cc
+++ b/extensions/browser/extension_function_dispatcher.cc
@@ -375,6 +375,8 @@ void ExtensionFunctionDispatcher::DispatchWithCallbackInternal(
   if (violation_error.empty()) {
     scoped_ptr<base::ListValue> args(params.arguments.DeepCopy());
 
+    // See crbug.com/39178.
+    ExtensionsBrowserClient::Get()->PermitExternalProtocolHandler();
     NotifyApiFunctionCalled(
         extension->id(), params.name, args.Pass(), browser_context_);
     function->Run();
diff --git a/extensions/browser/extensions_browser_client.h b/extensions/browser/extensions_browser_client.h
index 132e77a..2e3d26d 100644
--- a/extensions/browser/extensions_browser_client.h
+++ b/extensions/browser/extensions_browser_client.h
@@ -106,6 +106,10 @@ class ExtensionsBrowserClient {
   // version for later comparison.
   virtual bool DidVersionUpdate(content::BrowserContext* context) = 0;
 
+  // Permits an external protocol handler to be launched. See
+  // ExternalProtocolHandler::PermitLaunchUrl() in Chrome.
+  virtual void PermitExternalProtocolHandler() = 0;
+
   // Creates a new AppSorting instance.
   virtual scoped_ptr<AppSorting> CreateAppSorting() = 0;
 
diff --git a/extensions/browser/test_extensions_browser_client.cc b/extensions/browser/test_extensions_browser_client.cc
index 8a3fe23..739450b 100644
--- a/extensions/browser/test_extensions_browser_client.cc
+++ b/extensions/browser/test_extensions_browser_client.cc
@@ -107,6 +107,8 @@ bool TestExtensionsBrowserClient::DidVersionUpdate(BrowserContext* context) {
   return false;
 }
 
+void TestExtensionsBrowserClient::PermitExternalProtocolHandler() {}
+
 scoped_ptr<AppSorting> TestExtensionsBrowserClient::CreateAppSorting() {
   return scoped_ptr<AppSorting>();
 }
diff --git a/extensions/browser/test_extensions_browser_client.h b/extensions/browser/test_extensions_browser_client.h
index ac82589..19f33d7 100644
--- a/extensions/browser/test_extensions_browser_client.h
+++ b/extensions/browser/test_extensions_browser_client.h
@@ -51,6 +51,7 @@ class TestExtensionsBrowserClient : public ExtensionsBrowserClient {
   virtual scoped_ptr<ExtensionHostDelegate> CreateExtensionHostDelegate()
       OVERRIDE;
   virtual bool DidVersionUpdate(content::BrowserContext* context) OVERRIDE;
+  virtual void PermitExternalProtocolHandler() OVERRIDE;
   virtual scoped_ptr<AppSorting> CreateAppSorting() OVERRIDE;
   virtual bool IsRunningInForcedAppMode() OVERRIDE;
   virtual ApiActivityMonitor* GetApiActivityMonitor(