Update mojo sdk to rev d459e688a608f6eda850a23bb5e308a76ea51a47

BUG=None
TBR=jamesr@chromium.org

Review URL: https://codereview.chromium.org/1051303002

Cr-Commit-Position: refs/heads/master@{#324704}

99 files changed, 2057 insertions, 217 deletions

diff --git a/content/browser/geolocation/geolocation_service_impl.cc b/content/browser/geolocation/geolocation_service_impl.cc
index ffea846..7747cc4 100644
--- a/content/browser/geolocation/geolocation_service_impl.cc
+++ b/content/browser/geolocation/geolocation_service_impl.cc
@@ -69,6 +69,14 @@ GeolocationServiceImpl::GeolocationServiceImpl(
 }
 
 GeolocationServiceImpl::~GeolocationServiceImpl() {
+  // Make sure to respond to any pending callback even without a valid position.
+  if (!position_callback_.is_null()) {
+    if (!current_position_.valid) {
+      current_position_.error_code = MojoGeoposition::ErrorCode(
+          GEOPOSITION_ERROR_CODE_POSITION_UNAVAILABLE);
+    }
+    ReportCurrentPosition();
+  }
 }
 
 void GeolocationServiceImpl::PauseUpdates() {
diff --git a/content/browser/presentation/presentation_service_impl.cc b/content/browser/presentation/presentation_service_impl.cc
index 9e2fd22..2d6769e 100644
--- a/content/browser/presentation/presentation_service_impl.cc
+++ b/content/browser/presentation/presentation_service_impl.cc
@@ -25,6 +25,7 @@ PresentationServiceImpl::PresentationServiceImpl(
     : WebContentsObserver(web_contents),
       render_frame_host_(render_frame_host),
       delegate_(delegate),
+      is_start_session_pending_(false),
       next_request_session_id_(0),
       weak_factory_(this) {
   DCHECK(render_frame_host_);
@@ -39,6 +40,7 @@ PresentationServiceImpl::PresentationServiceImpl(
 PresentationServiceImpl::~PresentationServiceImpl() {
   if (delegate_)
     delegate_->RemoveObserver(this);
+  FlushNewSessionCallbacks();
 }
 
 // static
@@ -146,10 +148,13 @@ void PresentationServiceImpl::StartSession(
     return;
   }
 
-  queued_start_session_requests_.push_back(make_linked_ptr(
-      new StartSessionRequest(presentation_url, presentation_id, callback)));
-  if (queued_start_session_requests_.size() == 1)
-    DoStartSession(presentation_url, presentation_id, callback);
+  if (is_start_session_pending_) {
+    queued_start_session_requests_.push_back(make_linked_ptr(
+        new StartSessionRequest(presentation_url, presentation_id, callback)));
+    return;
+  }
+
+  DoStartSession(presentation_url, presentation_id, callback);
 }
 
 void PresentationServiceImpl::JoinSession(
@@ -175,15 +180,16 @@ void PresentationServiceImpl::JoinSession(
 }
 
 void PresentationServiceImpl::HandleQueuedStartSessionRequests() {
-  DCHECK(!queued_start_session_requests_.empty());
-  queued_start_session_requests_.pop_front();
-  if (!queued_start_session_requests_.empty()) {
-    const linked_ptr<StartSessionRequest>& request =
-        queued_start_session_requests_.front();
-    DoStartSession(request->presentation_url,
-                   request->presentation_id,
-                   request->callback);
+  if (queued_start_session_requests_.empty()) {
+    is_start_session_pending_ = false;
+    return;
   }
+  linked_ptr<StartSessionRequest> request =
+      queued_start_session_requests_.front();
+  queued_start_session_requests_.pop_front();
+  DoStartSession(request->presentation_url(),
+                 request->presentation_id(),
+                 request->PassCallback());
 }
 
 int PresentationServiceImpl::RegisterNewSessionCallback(
@@ -194,11 +200,19 @@ int PresentationServiceImpl::RegisterNewSessionCallback(
   return next_request_session_id_;
 }
 
+void PresentationServiceImpl::FlushNewSessionCallbacks() {
+  for (auto& pending_entry : pending_session_cbs_) {
+    InvokeNewSessionMojoCallbackWithError(*pending_entry.second);
+  }
+  pending_session_cbs_.clear();
+}
+
 void PresentationServiceImpl::DoStartSession(
     const std::string& presentation_url,
     const std::string& presentation_id,
     const NewSessionMojoCallback& callback) {
   int request_session_id = RegisterNewSessionCallback(callback);
+  is_start_session_pending_ = true;
   delegate_->StartSession(
       render_frame_host_->GetProcess()->GetID(),
       render_frame_host_->GetRoutingID(),
@@ -361,20 +375,12 @@ void PresentationServiceImpl::Reset() {
 
   default_presentation_url_.clear();
   default_presentation_id_.clear();
-  for (const auto& context_entry : availability_contexts_) {
-    context_entry.second->OnScreenAvailabilityChanged(false);
-  }
   availability_contexts_.clear();
-  for (auto& request_ptr : queued_start_session_requests_) {
-    InvokeNewSessionMojoCallbackWithError(request_ptr->callback);
-  }
   queued_start_session_requests_.clear();
-  for (auto& pending_entry : pending_session_cbs_) {
-    InvokeNewSessionMojoCallbackWithError(*pending_entry.second);
-  }
-  pending_session_cbs_.clear();
+  FlushNewSessionCallbacks();
 }
 
+// static
 void PresentationServiceImpl::InvokeNewSessionMojoCallbackWithError(
     const NewSessionMojoCallback& callback) {
   callback.Run(
@@ -396,6 +402,8 @@ PresentationServiceImpl::ScreenAvailabilityContext::ScreenAvailabilityContext(
 
 PresentationServiceImpl::ScreenAvailabilityContext::
 ~ScreenAvailabilityContext() {
+  // Ensure that pending callbacks are flushed.
+  OnScreenAvailabilityChanged(false);
 }
 
 void PresentationServiceImpl::ScreenAvailabilityContext::CallbackReceived(
@@ -452,12 +460,22 @@ PresentationServiceImpl::StartSessionRequest::StartSessionRequest(
     const std::string& presentation_url,
     const std::string& presentation_id,
     const NewSessionMojoCallback& callback)
-    : presentation_url(presentation_url),
-      presentation_id(presentation_id),
-      callback(callback) {
+    : presentation_url_(presentation_url),
+      presentation_id_(presentation_id),
+      callback_(callback) {
 }
 
 PresentationServiceImpl::StartSessionRequest::~StartSessionRequest() {
+  // Ensure that a pending callback is not dropped.
+  if (!callback_.is_null())
+    InvokeNewSessionMojoCallbackWithError(callback_);
+}
+
+PresentationServiceImpl::NewSessionMojoCallback
+PresentationServiceImpl::StartSessionRequest::PassCallback() {
+  NewSessionMojoCallback callback = callback_;
+  callback_.reset();
+  return callback;
 }
 
 }  // namespace content
diff --git a/content/browser/presentation/presentation_service_impl.h b/content/browser/presentation/presentation_service_impl.h
index 5b4972d..84962e7 100644
--- a/content/browser/presentation/presentation_service_impl.h
+++ b/content/browser/presentation/presentation_service_impl.h
@@ -110,15 +110,24 @@ class CONTENT_EXPORT PresentationServiceImpl
   };
 
   // Context for a StartSession request.
-  struct CONTENT_EXPORT StartSessionRequest {
+  class CONTENT_EXPORT StartSessionRequest {
+   public:
     StartSessionRequest(const std::string& presentation_url,
                         const std::string& presentation_id,
                         const NewSessionMojoCallback& callback);
     ~StartSessionRequest();
 
-    const std::string presentation_url;
-    const std::string presentation_id;
-    const NewSessionMojoCallback callback;
+    // Retrieves the pending callback from this request, transferring ownership
+    // to the caller.
+    NewSessionMojoCallback PassCallback();
+
+    const std::string& presentation_url() const { return presentation_url_; }
+    const std::string& presentation_id() const { return presentation_id_; }
+
+   private:
+    const std::string presentation_url_;
+    const std::string presentation_id_;
+    NewSessionMojoCallback callback_;
   };
 
   friend class PresentationServiceImplTest;
@@ -235,8 +244,11 @@ class CONTENT_EXPORT PresentationServiceImpl
   int RegisterNewSessionCallback(
     const NewSessionMojoCallback& callback);
 
+  // Flushes all pending new session callbacks with error responses.
+  void FlushNewSessionCallbacks();
+
   // Invokes |callback| with an error.
-  void InvokeNewSessionMojoCallbackWithError(
+  static void InvokeNewSessionMojoCallbackWithError(
       const NewSessionMojoCallback& callback);
 
   // Gets the ScreenAvailabilityContext for |presentation_url|, or creates one
@@ -259,6 +271,9 @@ class CONTENT_EXPORT PresentationServiceImpl
   // it is removed from head of the queue.
   std::deque<linked_ptr<StartSessionRequest>> queued_start_session_requests_;
 
+  // Indicates that a StartSession request is currently being processed.
+  bool is_start_session_pending_;
+
   int next_request_session_id_;
   base::hash_map<int, linked_ptr<NewSessionMojoCallback>> pending_session_cbs_;
 
diff --git a/third_party/mojo/mojom_bindings_generator.gypi b/third_party/mojo/mojom_bindings_generator.gypi
index e18ab05..948ce059 100644
--- a/third_party/mojo/mojom_bindings_generator.gypi
+++ b/third_party/mojo/mojom_bindings_generator.gypi
@@ -57,6 +57,7 @@
         '<@(mojom_import_args)',
         '-o', '<(SHARED_INTERMEDIATE_DIR)',
         '--java_output_directory=<(java_out_dir)',
+        '--dart_mojo_root=//third_party/mojo/src',
       ],
       'message': 'Generating Mojo bindings from <(RULE_INPUT_DIRNAME)/<(RULE_INPUT_ROOT).mojom',
       'process_outputs_as_sources': 1,
diff --git a/third_party/mojo/mojom_bindings_generator_explicit.gypi b/third_party/mojo/mojom_bindings_generator_explicit.gypi
index f65ec3e..3d2d80b 100644
--- a/third_party/mojo/mojom_bindings_generator_explicit.gypi
+++ b/third_party/mojo/mojom_bindings_generator_explicit.gypi
@@ -60,6 +60,7 @@
         '<@(mojom_import_args)',
         '-o', '<(SHARED_INTERMEDIATE_DIR)',
         '--java_output_directory=<(java_out_dir)',
+        '--dart_mojo_root=//third_party/mojo/src',
       ],
       'message': 'Generating Mojo bindings from <@(mojom_files)',
     }
diff --git a/third_party/mojo/src/mojo/public/BUILD.gn b/third_party/mojo/src/mojo/public/BUILD.gn
index 9ee041e..576625f 100644
--- a/third_party/mojo/src/mojo/public/BUILD.gn
+++ b/third_party/mojo/src/mojo/public/BUILD.gn
@@ -38,6 +38,7 @@ group("sdk") {
     "cpp/environment:standalone",
     "cpp/utility",
     "interfaces/application",
+    "interfaces/bindings",
     "js",
   ]
 }
diff --git a/third_party/mojo/src/mojo/public/VERSION b/third_party/mojo/src/mojo/public/VERSION
index 6979599..ba0a3bc 100644
--- a/third_party/mojo/src/mojo/public/VERSION
+++ b/third_party/mojo/src/mojo/public/VERSION
@@ -1 +1 @@
-912f52f69dadbe1e3cf9576f26731863770bcfc3
\ No newline at end of file
+d459e688a608f6eda850a23bb5e308a76ea51a47
\ No newline at end of file
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 2dac828..f6a9b1b 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/BUILD.gn
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/BUILD.gn
@@ -9,16 +9,9 @@ mojo_sdk_source_set("bindings") {
     "array.h",
     "binding.h",
     "error_handler.h",
-    "interface_ptr_info.h",
     "interface_ptr.h",
-    "map.h",
-    "message.h",
-    "message_filter.h",
-    "no_interface.h",
-    "strong_binding.h",
-    "string.h",
-    "struct_ptr.h",
-    "type_converter.h",
+    "interface_ptr_info.h",
+    "interface_request.h",
     "lib/array_internal.cc",
     "lib/array_internal.h",
     "lib/array_serialization.h",
@@ -55,6 +48,14 @@ mojo_sdk_source_set("bindings") {
     "lib/validate_params.h",
     "lib/validation_errors.cc",
     "lib/validation_errors.h",
+    "map.h",
+    "message.h",
+    "message_filter.h",
+    "no_interface.h",
+    "string.h",
+    "strong_binding.h",
+    "struct_ptr.h",
+    "type_converter.h",
   ]
 
   deps = [
@@ -71,9 +72,9 @@ mojo_sdk_source_set("callback") {
   sources = [
     "callback.h",
     "lib/callback_internal.h",
-    "lib/template_util.h",
     "lib/shared_data.h",
     "lib/shared_ptr.h",
+    "lib/template_util.h",
   ]
 
   mojo_sdk_deps = [ "mojo/public/cpp/system" ]
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/array_internal.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/array_internal.h
index eb25e35..f56319b 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/array_internal.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/array_internal.h
@@ -285,8 +285,13 @@ struct ArraySerializationHelper<P*, false> {
   }
 
  private:
+  template <typename T,
+            typename Params,
+            bool is_union = IsUnionDataType<T>::value>
+  struct ValidateCaller {};
+
   template <typename T, typename Params>
-  struct ValidateCaller {
+  struct ValidateCaller<T, Params, false> {
     static bool Run(const void* data, BoundsChecker* bounds_checker) {
       static_assert((IsSame<Params, NoValidateParams>::value),
                     "Struct type should not have array validate params");
@@ -295,8 +300,18 @@ struct ArraySerializationHelper<P*, false> {
     }
   };
 
+  template <typename T, typename Params>
+  struct ValidateCaller<T, Params, true> {
+    static bool Run(const void* data, BoundsChecker* bounds_checker) {
+      static_assert((IsSame<Params, NoValidateParams>::value),
+                    "Union type should not have array validate params");
+
+      return T::Validate(data, bounds_checker, true);
+    }
+  };
+
   template <typename Key, typename Value, typename Params>
-  struct ValidateCaller<Map_Data<Key, Value>, Params> {
+  struct ValidateCaller<Map_Data<Key, Value>, Params, false> {
     static bool Run(const void* data, BoundsChecker* bounds_checker) {
       return Map_Data<Key, Value>::template Validate<Params>(data,
                                                              bounds_checker);
@@ -304,7 +319,7 @@ struct ArraySerializationHelper<P*, false> {
   };
 
   template <typename T, typename Params>
-  struct ValidateCaller<Array_Data<T>, Params> {
+  struct ValidateCaller<Array_Data<T>, Params, false> {
     static bool Run(const void* data, BoundsChecker* bounds_checker) {
       return Array_Data<T>::template Validate<Params>(data, bounds_checker);
     }
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/array_serialization.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/array_serialization.h
index eacf298..827cb3f 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/array_serialization.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/array_serialization.h
@@ -45,11 +45,16 @@ inline void Deserialize_(internal::Array_Data<F>* data, Array<E>* output);
 
 namespace internal {
 
-template <typename E, typename F, bool move_only = IsMoveOnlyType<E>::value>
+template <typename E,
+          typename F,
+          bool move_only = IsMoveOnlyType<E>::value,
+          bool is_union =
+              IsUnionDataType<typename RemovePointer<F>::type>::value>
 struct ArraySerializer;
 
+// Handles serialization and deserialization of arrays of pod types.
 template <typename E, typename F>
-struct ArraySerializer<E, F, false> {
+struct ArraySerializer<E, F, false, false> {
   static_assert(sizeof(E) == sizeof(F), "Incorrect array serializer");
   static size_t GetSerializedSize(const Array<E>& input) {
     return sizeof(Array_Data<F>) + Align(input.size() * sizeof(E));
@@ -74,8 +79,9 @@ struct ArraySerializer<E, F, false> {
   }
 };
 
+// Serializes and deserializes arrays of bools.
 template <>
-struct ArraySerializer<bool, bool, false> {
+struct ArraySerializer<bool, bool, false, false> {
   static size_t GetSerializedSize(const Array<bool>& input) {
     return sizeof(Array_Data<bool>) + Align((input.size() + 7) / 8);
   }
@@ -102,8 +108,9 @@ struct ArraySerializer<bool, bool, false> {
   }
 };
 
+// Serializes and deserializes arrays of handles.
 template <typename H>
-struct ArraySerializer<ScopedHandleBase<H>, H, true> {
+struct ArraySerializer<ScopedHandleBase<H>, H, true, false> {
   static size_t GetSerializedSize(const Array<ScopedHandleBase<H>>& input) {
     return sizeof(Array_Data<H>) + Align(input.size() * sizeof(H));
   }
@@ -137,17 +144,17 @@ struct ArraySerializer<ScopedHandleBase<H>, H, true> {
 // This template must only apply to pointer mojo entity (structs and arrays).
 // This is done by ensuring that WrapperTraits<S>::DataType is a pointer.
 template <typename S>
-struct ArraySerializer<S,
-                       typename internal::EnableIf<
-                           internal::IsPointer<typename internal::WrapperTraits<
-                               S>::DataType>::value,
-                           typename internal::WrapperTraits<S>::DataType>::type,
-                       true> {
-  typedef typename internal::RemovePointer<
-      typename internal::WrapperTraits<S>::DataType>::type S_Data;
+struct ArraySerializer<
+    S,
+    typename EnableIf<IsPointer<typename WrapperTraits<S>::DataType>::value,
+                      typename WrapperTraits<S>::DataType>::type,
+    true,
+    false> {
+  typedef
+      typename RemovePointer<typename WrapperTraits<S>::DataType>::type S_Data;
   static size_t GetSerializedSize(const Array<S>& input) {
     size_t size = sizeof(Array_Data<S_Data*>) +
-                  input.size() * sizeof(internal::StructPointer<S_Data>);
+                  input.size() * sizeof(StructPointer<S_Data>);
     for (size_t i = 0; i < input.size(); ++i)
       size += GetSerializedSize_(input[i]);
     return size;
@@ -172,9 +179,7 @@ struct ArraySerializer<S,
                                   Array<S>* output) {
     Array<S> result(input->size());
     for (size_t i = 0; i < input->size(); ++i) {
-      S element;
-      Deserialize_(input->at(i), &element);
-      result[i] = element.Pass();
+      Deserialize_(input->at(i), &result[i]);
     }
     output->Swap(&result);
   }
@@ -184,7 +189,7 @@ struct ArraySerializer<S,
   struct SerializeCaller {
     static void Run(T input,
                     Buffer* buf,
-                    typename internal::WrapperTraits<T>::DataType* output) {
+                    typename WrapperTraits<T>::DataType* output) {
       static_assert((IsSame<Params, NoValidateParams>::value),
                     "Struct type should not have array validate params");
 
@@ -211,11 +216,49 @@ struct ArraySerializer<S,
   };
 };
 
+// Handles serialization and deserialization of arrays of unions.
+template <typename U, typename U_Data>
+struct ArraySerializer<U, U_Data, true, true> {
+  static size_t GetSerializedSize(const Array<U>& input) {
+    size_t size = sizeof(Array_Data<U_Data>);
+    for (size_t i = 0; i < input.size(); ++i) {
+      // GetSerializedSize_ will account for both the data in the union and the
+      // space in the array used to hold the union.
+      size += GetSerializedSize_(input[i], false);
+    }
+    return size;
+  }
+
+  template <bool element_is_nullable, typename ElementValidateParams>
+  static void SerializeElements(Array<U> input,
+                                Buffer* buf,
+                                Array_Data<U_Data>* output) {
+    for (size_t i = 0; i < input.size(); ++i) {
+      U_Data* result = output->storage() + i;
+      SerializeUnion_(input[i].Pass(), buf, &result, true);
+      MOJO_INTERNAL_DLOG_SERIALIZATION_WARNING(
+          !element_is_nullable && output->at(i).is_null(),
+          VALIDATION_ERROR_UNEXPECTED_NULL_POINTER,
+          MakeMessageWithArrayIndex("null in array expecting valid unions",
+                                    input.size(), i));
+    }
+  }
+
+  static void DeserializeElements(Array_Data<U_Data>* input, Array<U>* output) {
+    Array<U> result(input->size());
+    for (size_t i = 0; i < input->size(); ++i) {
+      Deserialize_(&input->at(i), &result[i]);
+    }
+    output->Swap(&result);
+  }
+};
+
+// Handles serialization and deserialization of arrays of strings.
 template <>
 struct ArraySerializer<String, String_Data*, false> {
   static size_t GetSerializedSize(const Array<String>& input) {
-    size_t size = sizeof(Array_Data<String_Data*>) +
-                  input.size() * sizeof(internal::StringPointer);
+    size_t size =
+        sizeof(Array_Data<String_Data*>) + input.size() * sizeof(StringPointer);
     for (size_t i = 0; i < input.size(); ++i)
       size += GetSerializedSize_(input[i]);
     return size;
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/bindings_internal.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/bindings_internal.h
index a8f95b2..4b5bb49 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/bindings_internal.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/bindings_internal.h
@@ -76,6 +76,18 @@ struct IsHandle {
   enum { value = IsBaseOf<Handle, H>::value };
 };
 
+template <typename T>
+struct IsUnionDataType {
+  template <typename U>
+  static YesType Test(const typename U::MojomUnionDataType*);
+
+  template <typename U>
+  static NoType Test(...);
+
+  static const bool value =
+      sizeof(Test<T>(0)) == sizeof(YesType) && !IsConst<T>::value;
+};
+
 template <typename T, bool move_only = IsMoveOnlyType<T>::value>
 struct WrapperTraits;
 
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 7c1d445..dfbd514 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
@@ -63,6 +63,9 @@ class Connector : public MessageReceiver {
   // a quiescent state.
   ScopedMessagePipeHandle PassMessagePipe();
 
+  // Is the connector bound to a MessagePipe handle?
+  bool is_valid() const { return message_pipe_.is_valid(); }
+
   // Waits for the next message on the pipe, blocking until one arrives or an
   // error happens. Returns |true| if a message has been delivered, |false|
   // otherwise.
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.cc b/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.cc
index da1e7e1..e64f1fa 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.cc
@@ -11,7 +11,7 @@ namespace internal {
 
 // ----------------------------------------------------------------------------
 
-class ResponderThunk : public MessageReceiver {
+class ResponderThunk : public MessageReceiverWithStatus {
  public:
   explicit ResponderThunk(const SharedData<Router*>& router)
       : router_(router), accept_was_invoked_(false) {}
@@ -44,6 +44,12 @@ class ResponderThunk : public MessageReceiver {
     return result;
   }
 
+  // MessageReceiverWithStatus implementation:
+  bool IsValid() override {
+    Router* router = router_.value();
+    return router && !router->encountered_error() && router->is_valid();
+  }
+
  private:
   SharedData<Router*> router_;
   bool accept_was_invoked_;
@@ -118,7 +124,7 @@ void Router::EnableTestingMode() {
 bool Router::HandleIncomingMessage(Message* message) {
   if (message->has_flag(kMessageExpectsResponse)) {
     if (incoming_receiver_) {
-      MessageReceiver* responder = new ResponderThunk(weak_self_);
+      MessageReceiverWithStatus* responder = new ResponderThunk(weak_self_);
       bool ok = incoming_receiver_->AcceptWithResponder(message, responder);
       if (!ok)
         delete responder;
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.h
index 8254bab..86b8897 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/router.h
@@ -24,7 +24,7 @@ class Router : public MessageReceiverWithResponder {
 
   // Sets the receiver to handle messages read from the message pipe that do
   // not have the kMessageIsResponse flag set.
-  void set_incoming_receiver(MessageReceiverWithResponder* receiver) {
+  void set_incoming_receiver(MessageReceiverWithResponderStatus* receiver) {
     incoming_receiver_ = receiver;
   }
 
@@ -38,6 +38,9 @@ class Router : public MessageReceiverWithResponder {
   // waiting to read from the pipe.
   bool encountered_error() const { return connector_.encountered_error(); }
 
+  // Is the router bound to a MessagePipe handle?
+  bool is_valid() const { return connector_.is_valid(); }
+
   void CloseMessagePipe() { connector_.CloseMessagePipe(); }
 
   ScopedMessagePipeHandle PassMessagePipe() {
@@ -81,7 +84,7 @@ class Router : public MessageReceiverWithResponder {
   FilterChain filters_;
   Connector connector_;
   SharedData<Router*> weak_self_;
-  MessageReceiverWithResponder* incoming_receiver_;
+  MessageReceiverWithResponderStatus* incoming_receiver_;
   ResponderMap responders_;
   uint64_t next_request_id_;
   bool testing_mode_;
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/template_util.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/template_util.h
index a90ee44..9a5788c 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/template_util.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/template_util.h
@@ -100,7 +100,9 @@ struct IsBaseOf {
 };
 
 template <class T>
-struct RemovePointer {};
+struct RemovePointer {
+  typedef T type;
+};
 template <class T>
 struct RemovePointer<T*> {
   typedef T type;
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/validation_errors.cc b/third_party/mojo/src/mojo/public/cpp/bindings/lib/validation_errors.cc
index 0ae4eca..15c2d3d 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/validation_errors.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/validation_errors.cc
@@ -40,6 +40,8 @@ const char* ValidationErrorToString(ValidationError error) {
       return "VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION";
     case VALIDATION_ERROR_MESSAGE_HEADER_MISSING_REQUEST_ID:
       return "VALIDATION_ERROR_MESSAGE_HEADER_MISSING_REQUEST_ID";
+    case VALIDATION_ERROR_MESSAGE_HEADER_UNKNOWN_METHOD:
+      return "VALIDATION_ERROR_MESSAGE_HEADER_UNKNOWN_METHOD";
     case VALIDATION_ERROR_DIFFERENT_SIZED_ARRAYS_IN_MAP:
       return "VALIDATION_ERROR_DIFFERENT_SIZED_ARRAYS_IN_MAP";
     case VALIDATION_ERROR_UNKNOWN_UNION_TAG:
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/lib/validation_errors.h b/third_party/mojo/src/mojo/public/cpp/bindings/lib/validation_errors.h
index d09f63b..da93598 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/lib/validation_errors.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/lib/validation_errors.h
@@ -44,6 +44,8 @@ enum ValidationError {
   // |flags| in the message header indicates that a request ID is required but
   // there isn't one.
   VALIDATION_ERROR_MESSAGE_HEADER_MISSING_REQUEST_ID,
+  // The |name| field in a message header contains an unexpected value.
+  VALIDATION_ERROR_MESSAGE_HEADER_UNKNOWN_METHOD,
   // Two parallel arrays which are supposed to represent a map have different
   // lengths.
   VALIDATION_ERROR_DIFFERENT_SIZED_ARRAYS_IN_MAP,
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/message.h b/third_party/mojo/src/mojo/public/cpp/bindings/message.h
index 80cd6d5..b763d9a 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/message.h
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/message.h
@@ -106,6 +106,39 @@ class MessageReceiverWithResponder : public MessageReceiver {
       MOJO_WARN_UNUSED_RESULT = 0;
 };
 
+// A MessageReceiver that is also able to provide status about the state
+// of the underlying MessagePipe to which it will be forwarding messages
+// received via the |Accept()| call.
+class MessageReceiverWithStatus : public MessageReceiver {
+ public:
+  ~MessageReceiverWithStatus() override {}
+
+  // Returns |true| if this MessageReceiver is currently bound to a MessagePipe,
+  // the pipe has not been closed, and the pipe has not encountered an error.
+  virtual bool IsValid() = 0;
+};
+
+// An alternative to MessageReceiverWithResponder for cases in which it
+// is necessary for the implementor of this interface to know about the status
+// of the MessagePipe which will carry the responses.
+class MessageReceiverWithResponderStatus : public MessageReceiver {
+ public:
+  ~MessageReceiverWithResponderStatus() override {}
+
+  // A variant on Accept that registers a MessageReceiverWithStatus (known as
+  // the responder) to handle the response message generated from the given
+  // message. Any of the responder's methods (Accept or IsValid) may be called
+  // during  AcceptWithResponder or some time after its return.
+  //
+  // NOTE: Upon returning true, AcceptWithResponder assumes ownership of
+  // |responder| and will delete it after calling |responder->Accept| or upon
+  // its own destruction.
+  //
+  virtual bool AcceptWithResponder(Message* message,
+                                   MessageReceiverWithStatus* responder)
+      MOJO_WARN_UNUSED_RESULT = 0;
+};
+
 // Read a single message from the pipe and dispatch to the given receiver.  The
 // receiver may be null, in which case the message is simply discarded.
 // Returns MOJO_RESULT_SHOULD_WAIT if the caller should wait on the handle to
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 6d09151..46c2e50 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
@@ -9,6 +9,7 @@ mojo_sdk_source_set("tests") {
 
   sources = [
     "array_unittest.cc",
+    "binding_callback_unittest.cc",
     "binding_unittest.cc",
     "bounds_checker_unittest.cc",
     "buffer_unittest.cc",
@@ -26,7 +27,6 @@ mojo_sdk_source_set("tests") {
     "string_unittest.cc",
     "struct_unittest.cc",
     "type_conversion_unittest.cc",
-    "union_unittest.cc",
     "validation_unittest.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
new file mode 100644
index 0000000..19e36b7
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/binding_callback_unittest.cc
@@ -0,0 +1,301 @@
+// 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/interface_ptr.h"
+#include "mojo/public/cpp/bindings/string.h"
+#include "mojo/public/cpp/environment/environment.h"
+#include "mojo/public/cpp/system/message_pipe.h"
+#include "mojo/public/cpp/test_support/test_support.h"
+#include "mojo/public/cpp/utility/run_loop.h"
+#include "mojo/public/interfaces/bindings/tests/sample_interfaces.mojom.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+///////////////////////////////////////////////////////////////////////////////
+//
+// The tests in this file are designed to test the interaction between a
+// Callback and its associated Binding. If a Callback is deleted before
+// being used we DCHECK fail--unless the associated Binding has already
+// been closed or deleted. This contract must be explained to the Mojo
+// application developer. For example it is the developer's responsibility to
+// ensure that the Binding is destroyed before an unused Callback is destroyed.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+namespace mojo {
+namespace test {
+namespace {
+
+// A Runnable object that saves the last value it sees via the
+// provided int32_t*. Used on the client side.
+class ValueSaver {
+ public:
+  explicit ValueSaver(int32_t* last_value_seen)
+      : last_value_seen_(last_value_seen) {}
+  void Run(int32_t x) const { *last_value_seen_ = x; }
+
+ private:
+  int32_t* const last_value_seen_;
+};
+
+// An implementation of sample::Provider used on the server side.
+// It only implements one of the methods: EchoInt().
+// All it does is save the values and Callbacks it sees.
+class InterfaceImpl : public sample::Provider {
+ public:
+  InterfaceImpl()
+      : last_server_value_seen_(0),
+        callback_saved_(new Callback<void(int32_t)>()) {}
+
+  ~InterfaceImpl() override {
+    if (callback_saved_) {
+      delete callback_saved_;
+    }
+  }
+
+  // Run's the callback previously saved from the last invocation
+  // of |EchoInt()|.
+  bool RunCallback() {
+    if (callback_saved_) {
+      callback_saved_->Run(last_server_value_seen_);
+      return true;
+    }
+    return false;
+  }
+
+  // Delete's the previously saved callback.
+  void DeleteCallback() {
+    delete callback_saved_;
+    callback_saved_ = nullptr;
+  }
+
+  // sample::Provider implementation
+
+  // Saves its two input values in member variables and does nothing else.
+  void EchoInt(int32_t x, const Callback<void(int32_t)>& callback) override {
+    last_server_value_seen_ = x;
+    *callback_saved_ = callback;
+  }
+
+  void EchoString(const String& a,
+                  const Callback<void(String)>& callback) override {
+    MOJO_CHECK(false) << "Not implemented.";
+  }
+
+  void EchoStrings(const String& a,
+                   const String& b,
+                   const Callback<void(String, String)>& callback) override {
+    MOJO_CHECK(false) << "Not implemented.";
+  }
+
+  void EchoMessagePipeHandle(
+      ScopedMessagePipeHandle a,
+      const Callback<void(ScopedMessagePipeHandle)>& callback) override {
+    MOJO_CHECK(false) << "Not implemented.";
+  }
+
+  void EchoEnum(sample::Enum a,
+                const Callback<void(sample::Enum)>& callback) override {
+    MOJO_CHECK(false) << "Not implemented.";
+  }
+
+  void resetLastServerValueSeen() { last_server_value_seen_ = 0; }
+
+  int32_t last_server_value_seen() const { return last_server_value_seen_; }
+
+ private:
+  int32_t last_server_value_seen_;
+  Callback<void(int32_t)>* callback_saved_;
+};
+
+class BindingCallbackTest : public testing::Test {
+ public:
+  ~BindingCallbackTest() override {}
+
+ protected:
+  int32_t last_client_callback_value_seen_;
+  sample::ProviderPtr interface_ptr_;
+
+  void PumpMessages() { loop_.RunUntilIdle(); }
+
+ private:
+  Environment env_;
+  RunLoop loop_;
+};
+
+// Tests that the InterfacePtr and the Binding can communicate with each
+// other normally.
+TEST_F(BindingCallbackTest, Basic) {
+  // Create the ServerImpl and the Binding.
+  InterfaceImpl server_impl;
+  Binding<sample::Provider> binding(&server_impl, GetProxy(&interface_ptr_));
+
+  // Initialize the test values.
+  server_impl.resetLastServerValueSeen();
+  last_client_callback_value_seen_ = 0;
+
+  // Invoke the Echo method.
+  interface_ptr_->EchoInt(7, ValueSaver(&last_client_callback_value_seen_));
+  PumpMessages();
+
+  // Check that server saw the correct value, but the client has not yet.
+  EXPECT_EQ(7, server_impl.last_server_value_seen());
+  EXPECT_EQ(0, last_client_callback_value_seen_);
+
+  // Now run the Callback.
+  server_impl.RunCallback();
+  PumpMessages();
+
+  // Check that the client has now seen the correct value.
+  EXPECT_EQ(7, last_client_callback_value_seen_);
+
+  // Initialize the test values again.
+  server_impl.resetLastServerValueSeen();
+  last_client_callback_value_seen_ = 0;
+
+  // Invoke the Echo method again.
+  interface_ptr_->EchoInt(13, ValueSaver(&last_client_callback_value_seen_));
+  PumpMessages();
+
+  // Check that server saw the correct value, but the client has not yet.
+  EXPECT_EQ(13, server_impl.last_server_value_seen());
+  EXPECT_EQ(0, last_client_callback_value_seen_);
+
+  // Now run the Callback again.
+  server_impl.RunCallback();
+  PumpMessages();
+
+  // Check that the client has now seen the correct value again.
+  EXPECT_EQ(13, last_client_callback_value_seen_);
+}
+
+// Tests that running the Callback after the Binding has been deleted
+// results in a clean failure.
+TEST_F(BindingCallbackTest, DeleteBindingThenRunCallback) {
+  // Create the ServerImpl.
+  InterfaceImpl server_impl;
+  {
+    // Create the binding in an inner scope so it can be deleted first.
+    Binding<sample::Provider> binding(&server_impl, GetProxy(&interface_ptr_));
+
+    // Initialize the test values.
+    server_impl.resetLastServerValueSeen();
+    last_client_callback_value_seen_ = 0;
+
+    // Invoke the Echo method.
+    interface_ptr_->EchoInt(7, ValueSaver(&last_client_callback_value_seen_));
+    PumpMessages();
+  }
+  // The binding has now been destroyed and the pipe is closed.
+
+  // Check that server saw the correct value, but the client has not yet.
+  EXPECT_EQ(7, server_impl.last_server_value_seen());
+  EXPECT_EQ(0, last_client_callback_value_seen_);
+
+  // Now try to run the Callback. This should do nothing since the pipe
+  // is closed.
+  EXPECT_TRUE(server_impl.RunCallback());
+  PumpMessages();
+
+  // Check that the client has still not seen the correct value.
+  EXPECT_EQ(0, last_client_callback_value_seen_);
+
+  // Attempt to invoke the method again and confirm that an error was
+  // encountered.
+  interface_ptr_->EchoInt(13, ValueSaver(&last_client_callback_value_seen_));
+  PumpMessages();
+  EXPECT_TRUE(interface_ptr_.encountered_error());
+}
+
+// Tests that deleting a Callback without running it after the corresponding
+// binding has already been deleted does not result in a crash.
+TEST_F(BindingCallbackTest, DeleteBindingThenDeleteCallback) {
+  // Create the ServerImpl.
+  InterfaceImpl server_impl;
+  {
+    // Create the binding in an inner scope so it can be deleted first.
+    Binding<sample::Provider> binding(&server_impl, GetProxy(&interface_ptr_));
+
+    // Initialize the test values.
+    server_impl.resetLastServerValueSeen();
+    last_client_callback_value_seen_ = 0;
+
+    // Invoke the Echo method.
+    interface_ptr_->EchoInt(7, ValueSaver(&last_client_callback_value_seen_));
+    PumpMessages();
+  }
+  // The binding has now been destroyed and the pipe is closed.
+
+  // Check that server saw the correct value, but the client has not yet.
+  EXPECT_EQ(7, server_impl.last_server_value_seen());
+  EXPECT_EQ(0, last_client_callback_value_seen_);
+
+  // Delete the callback without running it. This should not
+  // cause a problem because the insfrastructure can detect that the
+  // binding has already been destroyed and the pipe is closed.
+  server_impl.DeleteCallback();
+}
+
+// Tests that closing a Binding allows us to delete a callback
+// without running it without encountering a crash.
+TEST_F(BindingCallbackTest, CloseBindingBeforeDeletingCallback) {
+  // Create the ServerImpl and the Binding.
+  InterfaceImpl server_impl;
+  Binding<sample::Provider> binding(&server_impl, GetProxy(&interface_ptr_));
+
+  // Initialize the test values.
+  server_impl.resetLastServerValueSeen();
+  last_client_callback_value_seen_ = 0;
+
+  // Invoke the Echo method.
+  interface_ptr_->EchoInt(7, ValueSaver(&last_client_callback_value_seen_));
+  PumpMessages();
+
+  // Check that server saw the correct value, but the client has not yet.
+  EXPECT_EQ(7, server_impl.last_server_value_seen());
+  EXPECT_EQ(0, last_client_callback_value_seen_);
+
+  // Now close the Binding.
+  binding.Close();
+
+  // Delete the callback without running it. This should not
+  // cause a crash because the insfrastructure can detect that the
+  // binding has already been closed.
+  server_impl.DeleteCallback();
+
+  // Check that the client has still not seen the correct value.
+  EXPECT_EQ(0, last_client_callback_value_seen_);
+}
+
+// Tests that deleting a Callback without using it before the
+// Binding has been destroyed or closed results in a DCHECK.
+// Temporarily disabled due to
+// https://code.google.com/p/chromium/issues/detail?id=472218
+TEST_F(BindingCallbackTest, DISABLED_DeleteCallbackBeforeBindingDeathTest) {
+  // Create the ServerImpl and the Binding.
+  InterfaceImpl server_impl;
+  Binding<sample::Provider> binding(&server_impl, GetProxy(&interface_ptr_));
+
+  // Initialize the test values.
+  server_impl.resetLastServerValueSeen();
+  last_client_callback_value_seen_ = 0;
+
+  // Invoke the Echo method.
+  interface_ptr_->EchoInt(7, ValueSaver(&last_client_callback_value_seen_));
+  PumpMessages();
+
+  // Check that server saw the correct value, but the client has not yet.
+  EXPECT_EQ(7, server_impl.last_server_value_seen());
+  EXPECT_EQ(0, last_client_callback_value_seen_);
+
+#if !defined(NDEBUG) || defined(DCHECK_ALWAYS_ON)
+  // Delete the callback without running it. This should cause a crash in debug
+  // builds due to a DCHECK.
+  EXPECT_DEATH(server_impl.DeleteCallback(),
+               "Check failed: !callback_was_dropped.");
+#endif
+}
+
+}  // namespace
+}  // namespace test
+}  // namespace mojo
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 a1fe8e6..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
@@ -43,6 +43,10 @@ class ProviderImpl : public sample::Provider {
     callback.Run(a);
   }
 
+  void EchoInt(int32_t a, const EchoIntCallback& callback) override {
+    callback.Run(a);
+  }
+
   Binding<sample::Provider> binding_;
 };
 
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 ed3792f..d3d8ccb 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
@@ -47,19 +47,20 @@ class MessageAccumulator : public MessageReceiver {
   internal::MessageQueue* queue_;
 };
 
-class ResponseGenerator : public MessageReceiverWithResponder {
+class ResponseGenerator : public MessageReceiverWithResponderStatus {
  public:
   ResponseGenerator() {}
 
   bool Accept(Message* message) override { return false; }
 
   bool AcceptWithResponder(Message* message,
-                           MessageReceiver* responder) override {
+                           MessageReceiverWithStatus* responder) override {
     EXPECT_TRUE(message->has_flag(internal::kMessageExpectsResponse));
 
     bool result = SendResponse(
         message->name(), message->request_id(),
         reinterpret_cast<const char*>(message->payload()), responder);
+    EXPECT_TRUE(responder->IsValid());
     delete responder;
     return result;
   }
@@ -84,7 +85,7 @@ class LazyResponseGenerator : public ResponseGenerator {
   ~LazyResponseGenerator() override { delete responder_; }
 
   bool AcceptWithResponder(Message* message,
-                           MessageReceiver* responder) override {
+                           MessageReceiverWithStatus* responder) override {
     name_ = message->name();
     request_id_ = message->request_id();
     request_string_ =
@@ -95,6 +96,8 @@ class LazyResponseGenerator : public ResponseGenerator {
 
   bool has_responder() const { return !!responder_; }
 
+  bool responder_is_valid() const { return responder_->IsValid(); }
+
   // Send the response and delete the responder.
   void CompleteWithResponse() { Complete(true); }
 
@@ -112,7 +115,7 @@ class LazyResponseGenerator : public ResponseGenerator {
     responder_ = nullptr;
   }
 
-  MessageReceiver* responder_;
+  MessageReceiverWithStatus* responder_;
   uint32_t name_;
   uint64_t request_id_;
   std::string request_string_;
@@ -261,6 +264,7 @@ TEST_F(RouterTest, LazyResponses) {
   EXPECT_TRUE(message_queue.IsEmpty());
 
   // Send the response.
+  EXPECT_TRUE(generator.responder_is_valid());
   generator.CompleteWithResponse();
   PumpMessages();
 
@@ -283,6 +287,7 @@ TEST_F(RouterTest, LazyResponses) {
   EXPECT_TRUE(message_queue.IsEmpty());
 
   // Send the second response.
+  EXPECT_TRUE(generator.responder_is_valid());
   generator.CompleteWithResponse();
   PumpMessages();
 
@@ -358,6 +363,7 @@ TEST_F(RouterTest, LateResponse) {
     EXPECT_TRUE(generator.has_responder());
   }
 
+  EXPECT_FALSE(generator.responder_is_valid());
   generator.CompleteWithResponse();  // This should end up doing nothing.
 }
 
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/struct_unittest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/struct_unittest.cc
index 7f5a376..3fb4a28 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/struct_unittest.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/struct_unittest.cc
@@ -418,6 +418,5 @@ TEST_F(StructTest, Versioning_NewToOld) {
     EXPECT_TRUE(output->Equals(*expected_output));
   }
 }
-
 }  // namespace test
 }  // namespace mojo
diff --git a/third_party/mojo/src/mojo/public/cpp/bindings/tests/union_unittest.cc b/third_party/mojo/src/mojo/public/cpp/bindings/tests/union_unittest.cc
index aba7faa..ef9bac1 100644
--- a/third_party/mojo/src/mojo/public/cpp/bindings/tests/union_unittest.cc
+++ b/third_party/mojo/src/mojo/public/cpp/bindings/tests/union_unittest.cc
@@ -2,10 +2,14 @@
 // 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/array.h"
+#include "mojo/public/cpp/bindings/lib/array_internal.h"
+#include "mojo/public/cpp/bindings/lib/array_serialization.h"
 #include "mojo/public/cpp/bindings/lib/bounds_checker.h"
 #include "mojo/public/cpp/bindings/lib/fixed_buffer.h"
 #include "mojo/public/cpp/bindings/string.h"
 #include "mojo/public/cpp/environment/environment.h"
+#include "mojo/public/interfaces/bindings/tests/test_structs.mojom.h"
 #include "mojo/public/interfaces/bindings/tests/test_unions.mojom.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -104,12 +108,12 @@ TEST(UnionTest, SerializationPod) {
   PodUnionPtr pod1(PodUnion::New());
   pod1->set_f_int8(10);
 
-  size_t size = GetSerializedSize_(pod1);
+  size_t size = GetSerializedSize_(pod1, false);
   EXPECT_EQ(16U, size);
 
   mojo::internal::FixedBuffer buf(size);
-  internal::PodUnion_Data* data;
-  Serialize_(pod1.Pass(), &buf, &data);
+  internal::PodUnion_Data* data = nullptr;
+  SerializeUnion_(pod1.Pass(), &buf, &data, false);
 
   PodUnionPtr pod2;
   Deserialize_(data, &pod2);
@@ -119,27 +123,68 @@ TEST(UnionTest, SerializationPod) {
   EXPECT_EQ(pod2->which(), PodUnion::Tag::F_INT8);
 }
 
-TEST(UnionTest, ValidationJustWorksPod) {
+TEST(UnionTest, PodValidation) {
   PodUnionPtr pod(PodUnion::New());
   pod->set_f_int8(10);
 
-  size_t size = GetSerializedSize_(pod);
+  size_t size = GetSerializedSize_(pod, false);
   EXPECT_EQ(16U, size);
 
   mojo::internal::FixedBuffer buf(size);
-  internal::PodUnion_Data* data;
-  Serialize_(pod.Pass(), &buf, &data);
+  internal::PodUnion_Data* data = nullptr;
+  SerializeUnion_(pod.Pass(), &buf, &data, false);
   void* raw_buf = buf.Leak();
   mojo::internal::BoundsChecker bounds_checker(data,
                                                static_cast<uint32_t>(size), 0);
-  EXPECT_TRUE(internal::PodUnion_Data::Validate(raw_buf, &bounds_checker));
+  EXPECT_TRUE(
+      internal::PodUnion_Data::Validate(raw_buf, &bounds_checker, false));
   free(raw_buf);
 }
 
+TEST(UnionTest, SerializeNotNull) {
+  PodUnionPtr pod(PodUnion::New());
+  pod->set_f_int8(0);
+  size_t size = GetSerializedSize_(pod, false);
+  mojo::internal::FixedBuffer buf(size);
+  internal::PodUnion_Data* data = nullptr;
+  SerializeUnion_(pod.Pass(), &buf, &data, false);
+  EXPECT_FALSE(data->is_null());
+}
+
+TEST(UnionTest, SerializeIsNullInlined) {
+  PodUnionPtr pod;
+  size_t size = GetSerializedSize_(pod, false);
+  EXPECT_EQ(16U, size);
+  mojo::internal::FixedBuffer buf(size);
+  internal::PodUnion_Data* data = internal::PodUnion_Data::New(&buf);
+
+  // Check that dirty output buffers are handled correctly by serialization.
+  data->size = 16U;
+  data->tag = PodUnion::Tag::F_UINT16;
+  data->data.f_f_int16 = 20;
+
+  SerializeUnion_(pod.Pass(), &buf, &data, true);
+  EXPECT_TRUE(data->is_null());
+
+  PodUnionPtr pod2;
+  Deserialize_(data, &pod2);
+  EXPECT_TRUE(pod2.is_null());
+}
+
+TEST(UnionTest, SerializeIsNullNotInlined) {
+  PodUnionPtr pod;
+  size_t size = GetSerializedSize_(pod, false);
+  EXPECT_EQ(16U, size);
+  mojo::internal::FixedBuffer buf(size);
+  internal::PodUnion_Data* data = nullptr;
+  SerializeUnion_(pod.Pass(), &buf, &data, false);
+  EXPECT_EQ(nullptr, data);
+}
+
 TEST(UnionTest, NullValidation) {
   void* buf = nullptr;
   mojo::internal::BoundsChecker bounds_checker(buf, 0, 0);
-  EXPECT_TRUE(internal::PodUnion_Data::Validate(buf, &bounds_checker));
+  EXPECT_TRUE(internal::PodUnion_Data::Validate(buf, &bounds_checker, false));
 }
 
 TEST(UnionTest, OutOfAlignmentValidation) {
@@ -154,7 +199,7 @@ TEST(UnionTest, OutOfAlignmentValidation) {
       reinterpret_cast<internal::PodUnion_Data*>(buf);
   mojo::internal::BoundsChecker bounds_checker(data,
                                                static_cast<uint32_t>(size), 0);
-  EXPECT_FALSE(internal::PodUnion_Data::Validate(buf, &bounds_checker));
+  EXPECT_FALSE(internal::PodUnion_Data::Validate(buf, &bounds_checker, false));
   free(raw_buf);
 }
 
@@ -166,7 +211,8 @@ TEST(UnionTest, OOBValidation) {
   mojo::internal::BoundsChecker bounds_checker(data,
                                                static_cast<uint32_t>(size), 0);
   void* raw_buf = buf.Leak();
-  EXPECT_FALSE(internal::PodUnion_Data::Validate(raw_buf, &bounds_checker));
+  EXPECT_FALSE(
+      internal::PodUnion_Data::Validate(raw_buf, &bounds_checker, false));
   free(raw_buf);
 }
 
@@ -179,7 +225,8 @@ TEST(UnionTest, UnknownTagValidation) {
   mojo::internal::BoundsChecker bounds_checker(data,
                                                static_cast<uint32_t>(size), 0);
   void* raw_buf = buf.Leak();
-  EXPECT_FALSE(internal::PodUnion_Data::Validate(raw_buf, &bounds_checker));
+  EXPECT_FALSE(
+      internal::PodUnion_Data::Validate(raw_buf, &bounds_checker, false));
   free(raw_buf);
 }
 
@@ -222,10 +269,10 @@ TEST(UnionTest, StringSerialization) {
   String hello("hello world");
   pod1->set_f_string(hello);
 
-  size_t size = GetSerializedSize_(pod1);
+  size_t size = GetSerializedSize_(pod1, false);
   mojo::internal::FixedBuffer buf(size);
-  internal::ObjectUnion_Data* data;
-  Serialize_(pod1.Pass(), &buf, &data);
+  internal::ObjectUnion_Data* data = nullptr;
+  SerializeUnion_(pod1.Pass(), &buf, &data, false);
 
   ObjectUnionPtr pod2;
   Deserialize_(data, &pod2);
@@ -234,7 +281,7 @@ TEST(UnionTest, StringSerialization) {
   EXPECT_EQ(pod2->which(), ObjectUnion::Tag::F_STRING);
 }
 
-TEST(UnionTest, StringValidationNull) {
+TEST(UnionTest, NullStringValidation) {
   Environment environment;
   size_t size = sizeof(internal::ObjectUnion_Data);
   mojo::internal::FixedBuffer buf(size);
@@ -244,11 +291,12 @@ TEST(UnionTest, StringValidationNull) {
   mojo::internal::BoundsChecker bounds_checker(data,
                                                static_cast<uint32_t>(size), 0);
   void* raw_buf = buf.Leak();
-  EXPECT_FALSE(internal::ObjectUnion_Data::Validate(raw_buf, &bounds_checker));
+  EXPECT_FALSE(
+      internal::ObjectUnion_Data::Validate(raw_buf, &bounds_checker, false));
   free(raw_buf);
 }
 
-TEST(UnionTest, StringValidationPointerOverflow) {
+TEST(UnionTest, StringPointerOverflowValidation) {
   Environment environment;
   size_t size = sizeof(internal::ObjectUnion_Data);
   mojo::internal::FixedBuffer buf(size);
@@ -258,11 +306,12 @@ TEST(UnionTest, StringValidationPointerOverflow) {
   mojo::internal::BoundsChecker bounds_checker(data,
                                                static_cast<uint32_t>(size), 0);
   void* raw_buf = buf.Leak();
-  EXPECT_FALSE(internal::ObjectUnion_Data::Validate(raw_buf, &bounds_checker));
+  EXPECT_FALSE(
+      internal::ObjectUnion_Data::Validate(raw_buf, &bounds_checker, false));
   free(raw_buf);
 }
 
-TEST(UnionTest, StringValidationValidateString) {
+TEST(UnionTest, StringValidateOOB) {
   Environment environment;
   size_t size = 32;
   mojo::internal::FixedBuffer buf(size);
@@ -277,8 +326,203 @@ TEST(UnionTest, StringValidationValidateString) {
   array_header->num_elements = 20;
   mojo::internal::BoundsChecker bounds_checker(data, 32, 0);
   void* raw_buf = buf.Leak();
-  EXPECT_FALSE(internal::ObjectUnion_Data::Validate(raw_buf, &bounds_checker));
+  EXPECT_FALSE(
+      internal::ObjectUnion_Data::Validate(raw_buf, &bounds_checker, false));
+  free(raw_buf);
+}
+
+// TODO(azani): Move back in array_unittest.cc when possible.
+// Array tests
+TEST(UnionTest, PodUnionInArray) {
+  SmallStructPtr small_struct(SmallStruct::New());
+  small_struct->pod_union_array = Array<PodUnionPtr>(2);
+  small_struct->pod_union_array[0] = PodUnion::New();
+  small_struct->pod_union_array[1] = PodUnion::New();
+
+  small_struct->pod_union_array[0]->set_f_int8(10);
+  small_struct->pod_union_array[1]->set_f_int16(12);
+
+  EXPECT_EQ(10, small_struct->pod_union_array[0]->get_f_int8());
+  EXPECT_EQ(12, small_struct->pod_union_array[1]->get_f_int16());
+}
+
+TEST(UnionTest, PodUnionInArraySerialization) {
+  Environment environment;
+  Array<PodUnionPtr> array(2);
+  array[0] = PodUnion::New();
+  array[1] = PodUnion::New();
+
+  array[0]->set_f_int8(10);
+  array[1]->set_f_int16(12);
+  EXPECT_EQ(2U, array.size());
+
+  size_t size = GetSerializedSize_(array);
+  EXPECT_EQ(40U, size);
+
+  mojo::internal::FixedBuffer buf(size);
+  mojo::internal::Array_Data<internal::PodUnion_Data>* data;
+  SerializeArray_<mojo::internal::ArrayValidateParams<
+      0, false, mojo::internal::NoValidateParams>>(array.Pass(), &buf, &data);
+
+  Array<PodUnionPtr> array2;
+  Deserialize_(data, &array2);
+
+  EXPECT_EQ(2U, array2.size());
+
+  EXPECT_EQ(10, array2[0]->get_f_int8());
+  EXPECT_EQ(12, array2[1]->get_f_int16());
+}
+
+TEST(UnionTest, PodUnionInArraySerializationWithNull) {
+  Environment environment;
+  Array<PodUnionPtr> array(2);
+  array[0] = PodUnion::New();
+
+  array[0]->set_f_int8(10);
+  EXPECT_EQ(2U, array.size());
+
+  size_t size = GetSerializedSize_(array);
+  EXPECT_EQ(40U, size);
+
+  mojo::internal::FixedBuffer buf(size);
+  mojo::internal::Array_Data<internal::PodUnion_Data>* data;
+  SerializeArray_<mojo::internal::ArrayValidateParams<
+      0, true, mojo::internal::NoValidateParams>>(array.Pass(), &buf, &data);
+
+  Array<PodUnionPtr> array2;
+  Deserialize_(data, &array2);
+
+  EXPECT_EQ(2U, array2.size());
+
+  EXPECT_EQ(10, array2[0]->get_f_int8());
+  EXPECT_TRUE(array2[1].is_null());
+}
+
+// TODO(azani): Move back in struct_unittest.cc when possible.
+// Struct tests
+TEST(UnionTest, Clone_Union) {
+  Environment environment;
+  SmallStructPtr small_struct(SmallStruct::New());
+  small_struct->pod_union = PodUnion::New();
+  small_struct->pod_union->set_f_int8(10);
+
+  SmallStructPtr clone = small_struct.Clone();
+  EXPECT_EQ(10, clone->pod_union->get_f_int8());
+}
+
+// Serialization test of a struct with a union of plain old data.
+TEST(UnionTest, Serialization_UnionOfPods) {
+  Environment environment;
+  SmallStructPtr small_struct(SmallStruct::New());
+  small_struct->pod_union = PodUnion::New();
+  small_struct->pod_union->set_f_int32(10);
+
+  size_t size = GetSerializedSize_(small_struct);
+
+  mojo::internal::FixedBuffer buf(size);
+  internal::SmallStruct_Data* data = nullptr;
+  Serialize_(small_struct.Pass(), &buf, &data);
+
+  SmallStructPtr deserialized;
+  Deserialize_(data, &deserialized);
+
+  EXPECT_EQ(10, deserialized->pod_union->get_f_int32());
+}
+
+// Serialization test of a struct with a union of structs.
+TEST(UnionTest, Serialization_UnionOfObjects) {
+  Environment environment;
+  SmallObjStructPtr obj_struct(SmallObjStruct::New());
+  obj_struct->obj_union = ObjectUnion::New();
+  String hello("hello world");
+  obj_struct->obj_union->set_f_string(hello);
+
+  size_t size = GetSerializedSize_(obj_struct);
+
+  mojo::internal::FixedBuffer buf(size);
+  internal::SmallObjStruct_Data* data = nullptr;
+  Serialize_(obj_struct.Pass(), &buf, &data);
+
+  SmallObjStructPtr deserialized;
+  Deserialize_(data, &deserialized);
+
+  EXPECT_EQ(hello, deserialized->obj_union->get_f_string());
+}
+
+// Validation test of a struct with a union.
+TEST(UnionTest, Validation_UnionsInStruct) {
+  Environment environment;
+  SmallStructPtr small_struct(SmallStruct::New());
+  small_struct->pod_union = PodUnion::New();
+  small_struct->pod_union->set_f_int32(10);
+
+  size_t size = GetSerializedSize_(small_struct);
+
+  mojo::internal::FixedBuffer buf(size);
+  internal::SmallStruct_Data* data = nullptr;
+  Serialize_(small_struct.Pass(), &buf, &data);
+
+  void* raw_buf = buf.Leak();
+  mojo::internal::BoundsChecker bounds_checker(data, size, 0);
+  EXPECT_TRUE(internal::SmallStruct_Data::Validate(raw_buf, &bounds_checker));
+  free(raw_buf);
+}
+
+// Validation test of a struct union fails due to unknown union tag.
+TEST(UnionTest, Validation_PodUnionInStruct_Failure) {
+  Environment environment;
+  SmallStructPtr small_struct(SmallStruct::New());
+  small_struct->pod_union = PodUnion::New();
+  small_struct->pod_union->set_f_int32(10);
+
+  size_t size = GetSerializedSize_(small_struct);
+
+  mojo::internal::FixedBuffer buf(size);
+  internal::SmallStruct_Data* data = nullptr;
+  Serialize_(small_struct.Pass(), &buf, &data);
+  data->pod_union.tag = static_cast<internal::PodUnion_Data::PodUnion_Tag>(100);
+
+  void* raw_buf = buf.Leak();
+  mojo::internal::BoundsChecker bounds_checker(data, size, 0);
+  EXPECT_FALSE(internal::SmallStruct_Data::Validate(raw_buf, &bounds_checker));
   free(raw_buf);
 }
+
+// Validation fails due to non-nullable null union in struct.
+TEST(UnionTest, Validation_NullUnion_Failure) {
+  Environment environment;
+  SmallStructNonNullableUnionPtr small_struct(
+      SmallStructNonNullableUnion::New());
+
+  size_t size = GetSerializedSize_(small_struct);
+
+  mojo::internal::FixedBuffer buf(size);
+  internal::SmallStructNonNullableUnion_Data* data =
+      internal::SmallStructNonNullableUnion_Data::New(&buf);
+
+  void* raw_buf = buf.Leak();
+  mojo::internal::BoundsChecker bounds_checker(data, size, 0);
+  EXPECT_FALSE(internal::SmallStructNonNullableUnion_Data::Validate(
+      raw_buf, &bounds_checker));
+  free(raw_buf);
+}
+
+// Validation passes with nullable null union.
+TEST(UnionTest, Validation_NullableUnion) {
+  Environment environment;
+  SmallStructPtr small_struct(SmallStruct::New());
+
+  size_t size = GetSerializedSize_(small_struct);
+
+  mojo::internal::FixedBuffer buf(size);
+  internal::SmallStruct_Data* data = nullptr;
+  Serialize_(small_struct.Pass(), &buf, &data);
+
+  void* raw_buf = buf.Leak();
+  mojo::internal::BoundsChecker bounds_checker(data, size, 0);
+  EXPECT_TRUE(internal::SmallStruct_Data::Validate(raw_buf, &bounds_checker));
+  free(raw_buf);
+}
+
 }  // namespace test
 }  // namespace mojo
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 8139fe4..c15ff02 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
@@ -371,6 +371,16 @@ TEST_F(ValidationTest, Conformance) {
   RunValidationTests("conformance_", validators.GetHead());
 }
 
+// This test is similar to the Conformance test but for responses.
+TEST_F(ValidationTest, ResponseConformance) {
+  DummyMessageReceiver dummy_receiver;
+  mojo::internal::FilterChain validators(&dummy_receiver);
+  validators.Append<mojo::internal::MessageHeaderValidator>();
+  validators.Append<ConformanceTestInterface::ResponseValidator_>();
+
+  RunValidationTests("resp_conformance_", validators.GetHead());
+}
+
 // Test that InterfacePtr<X> applies the correct validators and they don't
 // conflict with each other:
 //   - MessageHeaderValidator
diff --git a/third_party/mojo/src/mojo/public/go/application/application_impl.go b/third_party/mojo/src/mojo/public/go/application/application_impl.go
new file mode 100644
index 0000000..43a1eb8
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/go/application/application_impl.go
@@ -0,0 +1,167 @@
+// 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.
+
+package application
+
+import (
+	"log"
+	"sync"
+
+	"mojo/public/go/bindings"
+	"mojo/public/go/system"
+
+	"mojo/public/interfaces/application/application"
+	sp "mojo/public/interfaces/application/service_provider"
+	"mojo/public/interfaces/application/shell"
+)
+
+// Delegate is an interface that your mojo application should implement.
+// All methods are called from the same goroutine to make sure that order of
+// calls matches the order of messages sent to underlying message pipe.
+type Delegate interface {
+	// Initialize is called exactly once before any other method.
+	Initialize(ctx Context)
+
+	// AcceptConnection is called when another application attempts to open
+	// a connection to this application. Close the connection if you no
+	// longer need it.
+	AcceptConnection(connection *Connection)
+
+	// Quit is called to request the application shut itself down
+	// gracefully.
+	Quit()
+}
+
+// Context is an interface to information about mojo application environment.
+type Context interface {
+	// URL returns the URL the application was found at, after all mappings,
+	// resolution, and redirects.
+	URL() string
+
+	// Args returns a list of initial configuration arguments, passed by the
+	// Shell.
+	Args() []string
+
+	// ConnectToApplication requests a new connection to an application. You
+	// should pass a list of services you want to provide to the requested
+	// application.
+	ConnectToApplication(remoteURL string, providedServices ...ServiceFactory) *OutgoingConnection
+}
+
+// ApplicationImpl is an utility class for communicating with the Shell, and
+// providing Services to clients.
+type ApplicationImpl struct {
+	shell *shell.ShellProxy
+	args  []string
+	url   string
+	// Pointer to the stub that runs this instance of ApplicationImpl.
+	runner   *bindings.Stub
+	quitOnce sync.Once
+
+	delegate Delegate
+	// Protects connections, that can be modified concurrently because of
+	// ConnectToApplication calls.
+	mu          sync.Mutex
+	connections []*Connection
+}
+
+// Run binds your mojo application to provided message pipe handle and runs it
+// until the application is terminated.
+func Run(delegate Delegate, applicationRequest system.MojoHandle) {
+	messagePipe := system.GetCore().AcquireNativeHandle(applicationRequest).ToMessagePipeHandle()
+	appRequest := application.ApplicationRequest{bindings.NewMessagePipeHandleOwner(messagePipe)}
+	impl := &ApplicationImpl{
+		delegate: delegate,
+	}
+	stub := application.NewApplicationStub(appRequest, impl, bindings.GetAsyncWaiter())
+	impl.runner = stub
+	for {
+		if err := stub.ServeRequest(); err != nil {
+			// TODO(rogulenko): don't log in case message pipe was closed
+			log.Println(err)
+			impl.RequestQuit()
+			break
+		}
+	}
+}
+
+// Mojo application implementation.
+func (impl *ApplicationImpl) Initialize(shellPointer shell.ShellPointer, args *[]string, url string) error {
+	impl.shell = shell.NewShellProxy(shellPointer, bindings.GetAsyncWaiter())
+	if args != nil {
+		impl.args = *args
+	}
+	impl.url = url
+	impl.delegate.Initialize(impl)
+	return nil
+}
+
+// Mojo application implementation.
+func (impl *ApplicationImpl) AcceptConnection(requestorURL string, services *sp.ServiceProviderRequest, exposedServices *sp.ServiceProviderPointer, resolvedURL string) error {
+	connection := newConnection(requestorURL, services, exposedServices, resolvedURL)
+	impl.delegate.AcceptConnection(connection)
+	impl.addConnection(connection)
+	return nil
+}
+
+// Mojo application implementation.
+func (impl *ApplicationImpl) RequestQuit() error {
+	impl.quitOnce.Do(func() {
+		impl.delegate.Quit()
+		impl.mu.Lock()
+		for _, c := range impl.connections {
+			c.Close()
+		}
+		impl.mu.Unlock()
+		impl.shell.Close_proxy()
+		impl.runner.Close()
+	})
+	return nil
+}
+
+// Context implementaion.
+func (impl *ApplicationImpl) URL() string {
+	return impl.url
+}
+
+// Context implementaion.
+func (impl *ApplicationImpl) Args() []string {
+	return impl.args
+}
+
+// Context implementaion.
+func (impl *ApplicationImpl) ConnectToApplication(remoteURL string, providedServices ...ServiceFactory) *OutgoingConnection {
+	servicesRequest, servicesPointer := sp.CreateMessagePipeForServiceProvider()
+	exposedServicesRequest, exposedServicesPointer := sp.CreateMessagePipeForServiceProvider()
+	if err := impl.shell.ConnectToApplication(remoteURL, &servicesRequest, &exposedServicesPointer); err != nil {
+		log.Printf("can't connect to %v: %v", remoteURL, err)
+		// In case of error message pipes sent through Shell are closed and
+		// the connection will work as if the remote application closed
+		// both ServiceProvider's pipes.
+	}
+	connection := newConnection(impl.url, &exposedServicesRequest, &servicesPointer, remoteURL)
+	impl.addConnection(connection)
+	return connection.ProvideServices(providedServices...)
+}
+
+// addConnection appends connections slice by a provided connection, removing
+// connections that have been closed.
+func (impl *ApplicationImpl) addConnection(c *Connection) {
+	impl.mu.Lock()
+	i := 0
+	for i < len(impl.connections) {
+		if impl.connections[i].isClosed {
+			last := len(impl.connections) - 1
+			impl.connections[i] = impl.connections[last]
+			impl.connections[last] = nil
+			impl.connections = impl.connections[:last]
+		} else {
+			i++
+		}
+	}
+	if !c.isClosed {
+		impl.connections = append(impl.connections, c)
+	}
+	impl.mu.Unlock()
+}
diff --git a/third_party/mojo/src/mojo/public/go/application/connection.go b/third_party/mojo/src/mojo/public/go/application/connection.go
new file mode 100644
index 0000000..5b2c629
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/go/application/connection.go
@@ -0,0 +1,174 @@
+// 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.
+
+package application
+
+import (
+	"log"
+
+	"mojo/public/go/bindings"
+	"mojo/public/go/system"
+
+	sp "mojo/public/interfaces/application/service_provider"
+)
+
+type connectionInfo struct {
+	requestorURL  string
+	connectionURL string
+}
+
+// RequestorURL returns the URL of application that established the connection.
+func (c *connectionInfo) RequestorURL() string {
+	return c.requestorURL
+}
+
+// ConnectionURL returns the URL that was used by the source application to
+// establish a connection to the destination application.
+func (c *connectionInfo) ConnectionURL() string {
+	return c.connectionURL
+}
+
+// ServiceRequest is an interface request for a specified mojo service.
+type ServiceRequest interface {
+	// Name returns the name of requested mojo service.
+	Name() string
+
+	// PassMessagePipe passes ownership of the underlying message pipe
+	// handle to the newly created handle object, invalidating the
+	// underlying handle object in the process.
+	PassMessagePipe() system.MessagePipeHandle
+}
+
+// ServiceFactory provides implementation of a mojo service.
+type ServiceFactory interface {
+	// Name returns the name of provided mojo service.
+	Name() string
+
+	// Create binds an implementation of mojo service to the provided
+	// message pipe and runs it.
+	Create(pipe system.MessagePipeHandle)
+}
+
+// Connection represents a connection to another application. An instance of
+// this struct is passed to Delegate's AcceptConnection() function each time a
+// connection is made to this application.
+type Connection struct {
+	connectionInfo
+	// Request for local services. Is valid until ProvideServices is called.
+	servicesRequest *sp.ServiceProviderRequest
+	// Indicates that ProvideServices function was already called.
+	servicesProvided   bool
+	localServices      *bindings.Stub
+	outgoingConnection *OutgoingConnection
+	isClosed           bool
+}
+
+func newConnection(requestorURL string, services *sp.ServiceProviderRequest, exposedServices *sp.ServiceProviderPointer, resolvedURL string) *Connection {
+	info := connectionInfo{
+		requestorURL,
+		resolvedURL,
+	}
+	var remoteServices *sp.ServiceProviderProxy
+	if exposedServices != nil {
+		remoteServices = sp.NewServiceProviderProxy(*exposedServices, bindings.GetAsyncWaiter())
+	}
+	return &Connection{
+		connectionInfo:  info,
+		servicesRequest: services,
+		outgoingConnection: &OutgoingConnection{
+			info,
+			remoteServices,
+		},
+	}
+}
+
+// ProvideServices starts a service provider on a separate goroutine that
+// provides given services to the remote application. Returns a pointer to
+// outgoing connection that can be used to connect to services provided by
+// remote application.
+// Panics if called more than once.
+func (c *Connection) ProvideServices(services ...ServiceFactory) *OutgoingConnection {
+	if c.servicesProvided {
+		panic("ProvideServices can be called only once")
+	}
+	c.servicesProvided = true
+	if c.servicesRequest == nil {
+		return c.outgoingConnection
+	}
+	if len(services) == 0 {
+		c.servicesRequest.PassMessagePipe().Close()
+		return c.outgoingConnection
+	}
+
+	provider := &serviceProviderImpl{
+		make(map[string]ServiceFactory),
+	}
+	for _, service := range services {
+		provider.AddService(service)
+	}
+	c.localServices = sp.NewServiceProviderStub(*c.servicesRequest, provider, bindings.GetAsyncWaiter())
+	go func() {
+		for {
+			if err := c.localServices.ServeRequest(); err != nil {
+				// TODO(rogulenko): don't log in case message pipe was closed
+				log.Println(err)
+				break
+			}
+		}
+	}()
+	return c.outgoingConnection
+}
+
+// Close closes both incoming and outgoing parts of the connection.
+func (c *Connection) Close() {
+	if c.servicesRequest != nil {
+		c.servicesRequest.Close()
+	}
+	if c.localServices != nil {
+		c.localServices.Close()
+	}
+	if c.outgoingConnection.remoteServices != nil {
+		c.outgoingConnection.remoteServices.Close_proxy()
+	}
+	c.isClosed = true
+}
+
+// OutgoingConnection represents outgoing part of connection to another
+// application. In order to close it close the |Connection| object that returned
+// this |OutgoingConnection|.
+type OutgoingConnection struct {
+	connectionInfo
+	remoteServices *sp.ServiceProviderProxy
+}
+
+// ConnectToService asks remote application to provide a service through the
+// message pipe endpoint supplied by the caller.
+func (c *OutgoingConnection) ConnectToService(request ServiceRequest) {
+	pipe := request.PassMessagePipe()
+	if c.remoteServices == nil {
+		pipe.Close()
+		return
+	}
+	c.remoteServices.ConnectToService(request.Name(), pipe)
+}
+
+// serviceProviderImpl is an implementation of mojo ServiceProvider interface.
+type serviceProviderImpl struct {
+	factories map[string]ServiceFactory
+}
+
+// Mojo ServiceProvider implementation.
+func (sp *serviceProviderImpl) ConnectToService(name string, messagePipe system.MessagePipeHandle) error {
+	factory, ok := sp.factories[name]
+	if !ok {
+		messagePipe.Close()
+		return nil
+	}
+	factory.Create(messagePipe)
+	return nil
+}
+
+func (sp *serviceProviderImpl) AddService(factory ServiceFactory) {
+	sp.factories[factory.Name()] = factory
+}
diff --git a/third_party/mojo/src/mojo/public/go/bindings/decoder.go b/third_party/mojo/src/mojo/public/go/bindings/decoder.go
index 34a230e..8f25c0b 100644
--- a/third_party/mojo/src/mojo/public/go/bindings/decoder.go
+++ b/third_party/mojo/src/mojo/public/go/bindings/decoder.go
@@ -290,7 +290,6 @@ func (d *Decoder) ReadString() (string, error) {
 // ReadPointer reads a pointer and reassigns first unclaimed byte index if the
 // pointer is not null.
 func (d *Decoder) ReadPointer() (uint64, error) {
-	oldEnd := d.state().offset
 	pointer, err := d.ReadUint64()
 	if err != nil {
 		return pointer, err
@@ -299,7 +298,7 @@ func (d *Decoder) ReadPointer() (uint64, error) {
 		return pointer, nil
 	}
 
-	newEnd := uint64(oldEnd) + pointer
+	newEnd := uint64(d.state().offset-8) + pointer
 	if newEnd >= uint64(len(d.buf)) {
 		return 0, fmt.Errorf("trying to access out of range memory")
 	}
diff --git a/third_party/mojo/src/mojo/public/go/bindings/encoder.go b/third_party/mojo/src/mojo/public/go/bindings/encoder.go
index 542cc21..e0a24fd 100644
--- a/third_party/mojo/src/mojo/public/go/bindings/encoder.go
+++ b/third_party/mojo/src/mojo/public/go/bindings/encoder.go
@@ -305,6 +305,8 @@ func (e *Encoder) WriteString(value string) error {
 
 // WritePointer writes a pointer to first unclaimed byte index.
 func (e *Encoder) WritePointer() error {
+	e.state().alignOffsetToBytes()
+	e.state().offset = align(e.state().offset, 8)
 	return e.WriteUint64(uint64(e.end - e.state().offset))
 }
 
diff --git a/third_party/mojo/src/mojo/public/go/system/message_pipe.go b/third_party/mojo/src/mojo/public/go/system/message_pipe.go
index 21b81ef..149b5be 100644
--- a/third_party/mojo/src/mojo/public/go/system/message_pipe.go
+++ b/third_party/mojo/src/mojo/public/go/system/message_pipe.go
@@ -49,7 +49,7 @@ func (h *messagePipe) WriteMessage(bytes []byte, handles []UntypedHandle, flags
 	if len(handles) != 0 {
 		rawHandles = make([]uint32, len(handles))
 		for i := 0; i < len(handles); i++ {
-			rawHandles[i] = uint32(handles[i].NativeHandle())
+			rawHandles[i] = uint32(handles[i].ReleaseNativeHandle())
 		}
 	}
 	h.core.mu.Lock()
diff --git a/third_party/mojo/src/mojo/public/interfaces/application/BUILD.gn b/third_party/mojo/src/mojo/public/interfaces/application/BUILD.gn
index 5b15344..32a6987 100644
--- a/third_party/mojo/src/mojo/public/interfaces/application/BUILD.gn
+++ b/third_party/mojo/src/mojo/public/interfaces/application/BUILD.gn
@@ -12,8 +12,8 @@ mojom("application") {
     "shell.mojom",
   ]
 
-  # This base dir ensures that Dart's Mojo SDK can be imported with, e.g.,
+  # The import_from ensures that Dart's Mojo SDK can be imported with, e.g.,
   # import 'package:mojo/public/dart/core.dart' even when the Mojo SDK lives
   # somewhere else in the source tree.
-  base_dir = mojo_root
+  import_from = mojo_root
 }
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/BUILD.gn b/third_party/mojo/src/mojo/public/interfaces/bindings/BUILD.gn
new file mode 100644
index 0000000..cf8a118
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/BUILD.gn
@@ -0,0 +1,11 @@
+# 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.
+
+import("../../tools/bindings/mojom.gni")
+
+mojom("bindings") {
+  sources = [
+    "interface_control_messages.mojom",
+  ]
+}
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/interface_control_messages.mojom b/third_party/mojo/src/mojo/public/interfaces/bindings/interface_control_messages.mojom
new file mode 100644
index 0000000..1ddccfc
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/interface_control_messages.mojom
@@ -0,0 +1,89 @@
+// 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.
+
+module mojo.internal;
+
+// For each message pipe representing a user-defined interface, some control 
+// functions are provided at the same end of the message pipe as the
+// user-defined interface, providing information about the user-defined
+// interface and controlling behavior of the message pipe.
+
+////////////////////////////////////////////////////////////////////////////////
+// Run@0xFFFFFFFF(RunInput input) => (RunOutput? output);
+//
+// This control function runs the input command. If the command is not
+// supported, |output| is set to null; otherwise |output| stores the result,
+// whose type depends on the input.
+//
+// TODO(yzshen): Once union support is ready, switch the following definition
+// to:
+// struct RunMessageParams {
+//   RunInput input;
+// };
+// union RunInput {
+//   QueryVersion query_version;
+// };
+//
+// struct RunResponseMessageParams {
+//   RunOutput? output;
+// };
+// union RunOutput {
+//   QueryVersionResult query_version_result;
+// };
+
+const uint32 kRunMessageId = 0xFFFFFFFF;
+
+struct RunMessageParams {
+  // The reserved fields make the layout compatible with the RunInput union
+  // described above.
+  uint32 reserved0;  // Must be set to 16.
+  uint32 reserved1;  // Must be set to 0;
+  QueryVersion query_version;
+};
+
+struct RunResponseMessageParams {
+  // The reserved fields make the layout compatible with the RunOutput union
+  // described above.
+  uint32 reserved0;  // Must be set to 16.
+  uint32 reserved1;  // Must be set to 0.
+  QueryVersionResult query_version_result;
+};
+
+// Queries the max supported version of the user-defined interface.
+struct QueryVersion {
+};
+struct QueryVersionResult {
+  uint32 version;
+};
+
+////////////////////////////////////////////////////////////////////////////////
+// RunOrClosePipe@0xFFFFFFFE(RunOrClosePipeInput input);
+//
+// This control function runs the input command. If the operation fails or the
+// command is not supported, the message pipe is closed.
+//
+// TODO(yzshen): Once union support is ready, switch the following definition
+// to:
+// struct RunOrClosePipeMessageParams {
+//   RunOrClosePipeInput input;
+// };
+// union RunOrClosePipeInput {
+//   RequireVersion require_version;
+// };
+
+const uint32 kRunOrClosePipeMessageId = 0xFFFFFFFE;
+
+struct RunOrClosePipeMessageParams {
+  // The reserved fields make the layout compatible with the RunOrClosePipeInput
+  // union described above.
+  uint32 reserved0;  // Must be set to 16.
+  uint32 reserved1;  // Must be set to 0.
+  RequireVersion require_version;
+};
+
+// If the specified version of the user-defined interface is not supported, the
+// function fails and the pipe is closed.
+struct RequireVersion {
+  uint32 version;
+};
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 dabc3f6..572b58a 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
@@ -18,7 +18,6 @@ mojom("test_interfaces") {
     "sample_service.mojom",
     "serialization_test_structs.mojom",
     "test_structs.mojom",
-    "test_unions.mojom",
     "validation_test_interfaces.mojom",
   ]
 }
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_invalid_flags.data b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_invalid_flag_combo.data
index 6c9654b..6c9654b 100644
--- a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_invalid_flags.data
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_invalid_flag_combo.data
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_invalid_flags.expected b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_invalid_flag_combo.expected
index 696c78d..696c78d 100644
--- a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_invalid_flags.expected
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_invalid_flag_combo.expected
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_no_such_method.data b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_no_such_method.data
new file mode 100644
index 0000000..a1b034c
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_no_such_method.data
@@ -0,0 +1,5 @@
+[dist4]message_header  // num_bytes
+[u4]2                  // version number
+[u4]9999               // There is no Method9999.
+[u4]0                  // flags
+[anchr]message_header
\ No newline at end of file
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_no_such_method.expected b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_no_such_method.expected
new file mode 100644
index 0000000..a32d895
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_msghdr_no_such_method.expected
@@ -0,0 +1 @@
+VALIDATION_ERROR_MESSAGE_HEADER_UNKNOWN_METHOD
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags.data b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags.data
new file mode 100644
index 0000000..07cf4c1
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags.data
@@ -0,0 +1,6 @@
+[dist4]message_header  // num_bytes
+[u4]3                  // version
+[u4]0                  // name
+[u4]2                  // flags: kMessageIsResponse is set in a request.
+[u8]1                  // request_id
+[anchr]message_header
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags.expected b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags.expected
new file mode 100644
index 0000000..696c78d
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags.expected
@@ -0,0 +1 @@
+VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags2.data b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags2.data
new file mode 100644
index 0000000..2b59165
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags2.data
@@ -0,0 +1,7 @@
+[dist4]message_header  // num_bytes
+[u4]3                  // version
+[u4]0                  // name
+[u4]1                  // flags: kMessageExpectsResponse is set in a request
+                       // for a method that does not take a response.
+[u8]1                  // request_id
+[anchr]message_header
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags2.expected b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags2.expected
new file mode 100644
index 0000000..696c78d
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd0_invalid_request_flags2.expected
@@ -0,0 +1 @@
+VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd12_invalid_request_flags.data b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd12_invalid_request_flags.data
new file mode 100644
index 0000000..1c80196
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd12_invalid_request_flags.data
@@ -0,0 +1,7 @@
+[dist4]message_header  // num_bytes
+[u4]3                  // version
+[u4]12                 // name
+[u4]0                  // flags: kMessageExpectsResponse is not set but 
+                       // expected.
+[u8]1                  // request_id
+[anchr]message_header
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd12_invalid_request_flags.expected b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd12_invalid_request_flags.expected
new file mode 100644
index 0000000..696c78d
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/conformance_mthd12_invalid_request_flags.expected
@@ -0,0 +1 @@
+VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags1.data b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags1.data
new file mode 100644
index 0000000..d9ca38e
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags1.data
@@ -0,0 +1,6 @@
+[dist4]message_header  // num_bytes
+[u4]3                  // version
+[u4]12                 // name
+[u4]0                  // flags: kMessageIsResponse is not set in a response.
+[u8]1                  // request_id
+[anchr]message_header
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags1.expected b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags1.expected
new file mode 100644
index 0000000..696c78d
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags1.expected
@@ -0,0 +1 @@
+VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags2.data b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags2.data
new file mode 100644
index 0000000..7587fc5
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags2.data
@@ -0,0 +1,6 @@
+[dist4]message_header  // num_bytes
+[u4]3                  // version
+[u4]12                 // name
+[u4]1                  // flags: kMessageExpectsResponse is set in a response.
+[u8]1                  // request_id
+[anchr]message_header
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags2.expected b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags2.expected
new file mode 100644
index 0000000..696c78d
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_invalid_response_flags2.expected
@@ -0,0 +1 @@
+VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_no_such_method.data b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_no_such_method.data
new file mode 100644
index 0000000..cc9cc8b
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_no_such_method.data
@@ -0,0 +1,6 @@
+[dist4]message_header  // num_bytes
+[u4]3                  // version
+[u4]11                 // name: Method11 does not have a response message.
+[u4]2                  // flags: kMessageIsResponse
+[u8]1                  // request_id
+[anchr]message_header
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_no_such_method.expected b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_no_such_method.expected
new file mode 100644
index 0000000..65a48b3
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/data/validation/resp_conformance_msghdr_no_such_method.expected
@@ -0,0 +1 @@
+VALIDATION_ERROR_MESSAGE_HEADER_UNKNOWN_METHOD
\ No newline at end of file
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/sample_interfaces.mojom b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/sample_interfaces.mojom
index 52589a9..c3cd1b2a 100644
--- a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/sample_interfaces.mojom
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/sample_interfaces.mojom
@@ -18,4 +18,5 @@ interface Provider {
   EchoStrings(string a, string b) => (string a, string b);
   EchoMessagePipeHandle(handle<message_pipe> a) => (handle<message_pipe> a);
   EchoEnum(Enum a) => (Enum a);
+  EchoInt(int32 a) => (int32 a);
 };
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 eae8ce6..7250f65 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
@@ -23,3 +23,22 @@ union ObjectUnion {
   int8   f_int8;
   string f_string;
 };
+
+struct DummyStruct {
+  int8 f_int8;
+};
+
+struct SmallStruct {
+  DummyStruct? dummy_struct;
+  PodUnion? pod_union;
+  array<PodUnion>? pod_union_array;
+  array<DummyStruct>? s_array;
+};
+
+struct SmallStructNonNullableUnion {
+  PodUnion pod_union;
+};
+
+struct SmallObjStruct {
+  ObjectUnion obj_union;
+};
diff --git a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom
index 13d0b52..cd5e1aa 100644
--- a/third_party/mojo/src/mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom
+++ b/third_party/mojo/src/mojo/public/interfaces/bindings/tests/validation_test_interfaces.mojom
@@ -54,6 +54,7 @@ interface ConformanceTestInterface {
   Method9(array<array<handle?>>? param0);
   Method10(map<string, uint8> param0);
   Method11(StructG param0);
+  Method12(float param0) => (float param0);
 };
 
 struct BasicStruct {
diff --git a/third_party/mojo/src/mojo/public/js/validation_unittests.js b/third_party/mojo/src/mojo/public/js/validation_unittests.js
index a04879c..4fdb5d4 100644
--- a/third_party/mojo/src/mojo/public/js/validation_unittests.js
+++ b/third_party/mojo/src/mojo/public/js/validation_unittests.js
@@ -225,11 +225,19 @@ define([
     expect(testFiles.length).toBeGreaterThan(0);
 
     for (var i = 0; i < testFiles.length; i++) {
-      // TODO(hansmuller, yzshen): Temporarily skipping:
-      //   - array pointer overflow tests;
-      //   - struct versioning tests (tests with "mthd11" in the name).
+      // TODO(hansmuller) Temporarily skipping array pointer overflow tests
+      // because JS numbers are limited to 53 bits.
+      // TODO(yzshen) Skipping struct versioning tests (tests with "mthd11"
+      // in the name) because the feature is not supported in JS yet.
+      // TODO(rudominer): Temporarily skipping 'no-such-method',
+      // 'invalid_request_flags', and 'invalid_response_flags' until additional
+      // logic in *RequestValidator and *ResponseValidator is ported from
+      // cpp to js.
       if (testFiles[i].indexOf("overflow") != -1 ||
-          testFiles[i].indexOf("mthd11") != -1) {
+          testFiles[i].indexOf("mthd11") != -1 ||
+          testFiles[i].indexOf("no_such_method") != -1 ||
+          testFiles[i].indexOf("invalid_request_flags") != -1 ||
+          testFiles[i].indexOf("invalid_response_flags") != -1) {
         console.log("[Skipping " + testFiles[i] + "]");
         continue;
       }
@@ -257,12 +265,6 @@ define([
     expect(testFiles.length).toBeGreaterThan(0);
 
     for (var i = 0; i < testFiles.length; i++) {
-      // TODO(hansmuller): Temporarily skipping array pointer overflow tests.
-      if (testFiles[i].indexOf("overflow") != -1) {
-        console.log("[Skipping " + testFiles[i] + "]");
-        continue;
-      }
-
       var testMessage = readTestMessage(testFiles[i]);
       var handles = new Array(testMessage.handleCount);
       var testMessagePipe = new core.createMessagePipe();
diff --git a/third_party/mojo/src/mojo/public/tools/BUILD.gn b/third_party/mojo/src/mojo/public/tools/BUILD.gn
index 607ee7a..c8ea1e3 100644
--- a/third_party/mojo/src/mojo/public/tools/BUILD.gn
+++ b/third_party/mojo/src/mojo/public/tools/BUILD.gn
@@ -35,15 +35,25 @@ if (mojo_use_prebuilt_network_service) {
 
   copy("copy_network_service_apptests") {
     filename = "network_service_apptests.mojo"
-    if (is_android) {
+    if (defined(mojo_prebuilt_network_service_apptests_location) &&
+        mojo_prebuilt_network_service_apptests_location != "") {
       sources = [
-        "prebuilt/network_service_apptests/android-arm/$filename",
+        "$mojo_prebuilt_network_service_apptests_location",
       ]
     } else {
-      assert(is_linux)
-      sources = [
-        "prebuilt/network_service_apptests/linux-x64/$filename",
-      ]
+      if (is_android) {
+        assert(
+            cpu_arch == "arm",
+            "Only arm version prebuilt netowrk_service_apptests.mojo is available.")
+        sources = [
+          "prebuilt/network_service_apptests/android-arm/$filename",
+        ]
+      } else {
+        assert(is_linux)
+        sources = [
+          "prebuilt/network_service_apptests/linux-x64/$filename",
+        ]
+      }
     }
     outputs = [
       "$root_out_dir/$filename",
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl
index 44d1428..fd6b643 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_definition.tmpl
@@ -46,7 +46,7 @@ class {{class_name}}_{{method.name}}_ForwardToCallback
       const {{class_name}}::{{method.name}}Callback& callback)
       : callback_(callback) {
   }
-  virtual bool Accept(mojo::Message* message) override;
+  bool Accept(mojo::Message* message) override;
  private:
   {{class_name}}::{{method.name}}Callback callback_;
   MOJO_DISALLOW_COPY_AND_ASSIGN({{class_name}}_{{method.name}}_ForwardToCallback);
@@ -115,31 +115,33 @@ class {{class_name}}_{{method.name}}_ProxyToResponder
     : public {{class_name}}::{{method.name}}Callback::Runnable {
  public:
   virtual ~{{class_name}}_{{method.name}}_ProxyToResponder() {
+    // Is the Mojo application destroying the callback without running it
+    // and without first closing the pipe?
+    bool callback_was_dropped = responder_ && responder_->IsValid();
+    // If the Callback was dropped then deleting the responder will close
+    // the pipe so the calling application knows to stop waiting for a reply.
     delete responder_;
-    // TODO(rudominer) DCHECK if |was_run_| is false and we don't have evidence
-    // that we are in a legitamte shutdown case such as the Connector detected
-    // an error or Close() was invoked.
+    MOJO_DCHECK(!callback_was_dropped)  << "The callback passed to "
+        "{{class_name}}::{{method.name}}({%- if method.parameters -%}{{pass_params(method.parameters)}}, {% endif -%}callback) "
+        "was never run.";
   }
 
   {{class_name}}_{{method.name}}_ProxyToResponder(
       uint64_t request_id,
-      mojo::MessageReceiver* responder)
+      mojo::MessageReceiverWithStatus* responder)
       : request_id_(request_id),
-        responder_(responder),
-        was_run_(false) {
+        responder_(responder) {
   }
 
-  virtual void Run({{interface_macros.declare_params("in_", method.response_parameters)}}) const override;
+  void Run({{interface_macros.declare_params("in_", method.response_parameters)}}) const override;
 
  private:
   uint64_t request_id_;
-  mutable mojo::MessageReceiver* responder_;
-  mutable bool was_run_;
+  mutable mojo::MessageReceiverWithStatus* responder_;
   MOJO_DISALLOW_COPY_AND_ASSIGN({{class_name}}_{{method.name}}_ProxyToResponder);
 };
 void {{class_name}}_{{method.name}}_ProxyToResponder::Run(
     {{interface_macros.declare_params("in_", method.response_parameters)}}) const {
-  was_run_ = true;
   {{struct_macros.get_serialized_size(response_params_struct, "in_%s")}}
   mojo::internal::ResponseMessageBuilder builder(
       {{message_name}}, size, request_id_);
@@ -159,6 +161,8 @@ void {{class_name}}_{{method.name}}_ProxyToResponder::Run(
     : sink_(nullptr) {
 }
 
+{{class_name}}Stub::~{{interface.name}}Stub() {}
+
 {#--- Stub definition #}
 
 bool {{class_name}}Stub::Accept(mojo::Message* message) {
@@ -188,7 +192,7 @@ bool {{class_name}}Stub::Accept(mojo::Message* message) {
 }
 
 bool {{class_name}}Stub::AcceptWithResponder(
-    mojo::Message* message, mojo::MessageReceiver* responder) {
+    mojo::Message* message, mojo::MessageReceiverWithStatus* responder) {
 {%- if interface.methods %}
   switch (message->header()->name) {
 {%-   for method in interface.methods %}
@@ -227,16 +231,25 @@ bool {{class_name}}Stub::AcceptWithResponder(
 
 bool {{class_name}}RequestValidator::Accept(mojo::Message* message) {
 {%- if interface.methods %}
+  if (message->has_flag(mojo::internal::kMessageIsResponse)) {
+    ReportValidationError(
+        mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION);
+    return false;
+  }
   switch (message->header()->name) {
 {%-   for method in interface.methods %}
     case internal::k{{class_name}}_{{method.name}}_Name: {
 {%-     if method.response_parameters != None %}
-      if (!message->has_flag(mojo::internal::kMessageExpectsResponse))
-        break;
+      if (!message->has_flag(mojo::internal::kMessageExpectsResponse)) {
+        ReportValidationError(
+            mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION);
+        return false;
+      }
 {%-     else %}
-      if (message->has_flag(mojo::internal::kMessageExpectsResponse) ||
-          message->has_flag(mojo::internal::kMessageIsResponse)) {
-        break;
+      if (message->has_flag(mojo::internal::kMessageExpectsResponse)) {
+        ReportValidationError(
+            mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION);
+        return false;
       }
 {%-     endif %}
       mojo::internal::BoundsChecker bounds_checker(
@@ -249,6 +262,12 @@ bool {{class_name}}RequestValidator::Accept(mojo::Message* message) {
       break;
     }
 {%-   endfor %}
+    default: {
+      // Unrecognized message.
+      ReportValidationError(
+          mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_UNKNOWN_METHOD);
+      return false;
+    }
   }
 {%- endif %}
 
@@ -264,11 +283,14 @@ bool {{class_name}}RequestValidator::Accept(mojo::Message* message) {
 
 bool {{class_name}}ResponseValidator::Accept(mojo::Message* message) {
 {%- if interface.methods %}
+  if (!message->has_flag(mojo::internal::kMessageIsResponse)) {
+    ReportValidationError(
+        mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_INVALID_FLAG_COMBINATION);
+    return false;
+  }
   switch (message->header()->name) {
 {%-   for method in interface.methods if method.response_parameters != None %}
     case internal::k{{class_name}}_{{method.name}}_Name: {
-      if (!message->has_flag(mojo::internal::kMessageIsResponse))
-        break;
       mojo::internal::BoundsChecker bounds_checker(
           message->payload(), message->payload_num_bytes(),
           message->handles()->size());
@@ -279,6 +301,12 @@ bool {{class_name}}ResponseValidator::Accept(mojo::Message* message) {
       break;
     }
 {%-   endfor %}
+    default: {
+      // Unrecognized message.
+      ReportValidationError(
+          mojo::internal::VALIDATION_ERROR_MESSAGE_HEADER_UNKNOWN_METHOD);
+      return false;
+    }
   }
 {%- endif %}
 
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_proxy_declaration.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_proxy_declaration.tmpl
index 6b8e7c5..420f6e8 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_proxy_declaration.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_proxy_declaration.tmpl
@@ -4,7 +4,7 @@ class {{interface.name}}Proxy : public {{interface.name}} {
   explicit {{interface.name}}Proxy(mojo::MessageReceiverWithResponder* receiver);
 
 {%- for method in interface.methods %}
-  virtual void {{method.name}}(
+  void {{method.name}}(
       {{interface_macros.declare_request_params("", method)}}
   ) override;
 {%- endfor %}
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_request_validator_declaration.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_request_validator_declaration.tmpl
index 2239b69..29917ea 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_request_validator_declaration.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_request_validator_declaration.tmpl
@@ -2,5 +2,5 @@ class {{interface.name}}RequestValidator : public mojo::MessageFilter {
  public:
   explicit {{interface.name}}RequestValidator(mojo::MessageReceiver* sink = nullptr);
 
-  virtual bool Accept(mojo::Message* message) override;
+  bool Accept(mojo::Message* message) override;
 };
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_response_validator_declaration.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_response_validator_declaration.tmpl
index 801603d..5893bfd 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_response_validator_declaration.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_response_validator_declaration.tmpl
@@ -2,5 +2,5 @@ class {{interface.name}}ResponseValidator : public mojo::MessageFilter {
  public:
   explicit {{interface.name}}ResponseValidator(mojo::MessageReceiver* sink = nullptr);
 
-  virtual bool Accept(mojo::Message* message) override;
+  bool Accept(mojo::Message* message) override;
 };
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_stub_declaration.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_stub_declaration.tmpl
index afc6504..05a2495 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_stub_declaration.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/interface_stub_declaration.tmpl
@@ -1,12 +1,13 @@
-class {{interface.name}}Stub : public mojo::MessageReceiverWithResponder {
+class {{interface.name}}Stub : public mojo::MessageReceiverWithResponderStatus {
  public:
   {{interface.name}}Stub();
+  ~{{interface.name}}Stub() override;
   void set_sink({{interface.name}}* sink) { sink_ = sink; }
   {{interface.name}}* sink() { return sink_; }
 
-  virtual bool Accept(mojo::Message* message) override;
-  virtual bool AcceptWithResponder(mojo::Message* message,
-                                   mojo::MessageReceiver* responder) override;
+  bool Accept(mojo::Message* message) override;
+  bool AcceptWithResponder(mojo::Message* message,
+      mojo::MessageReceiverWithStatus* responder) override;
 
  private:
   {{interface.name}}* sink_;
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/module-internal.h.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/module-internal.h.tmpl
index d9a398a..b4b4df8 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/module-internal.h.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/module-internal.h.tmpl
@@ -50,15 +50,17 @@ class {{union.name}}_Data;
 
 #pragma pack(push, 1)
 
+{#--- Unions must be declared first because they can be members of structs #}
+{#--- Union class declarations #}
+{%  for union in unions %}
+{%    include "union_declaration.tmpl" %}
+{%- endfor %}
+
 {#--- Class declarations #}
 {%  for struct in structs %}
 {%    include "struct_declaration.tmpl" %}
 {%- endfor %}
 
-{%  for union in unions %}
-{%    include "union_declaration.tmpl" %}
-{%- endfor %}
-
 #pragma pack(pop)
 
 }  // namespace internal
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 0312002..503e19d 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
@@ -63,6 +63,12 @@ typedef mojo::StructPtr<{{union.name}}> {{union.name}}Ptr;
 {%    endif %}
 {%- endfor %}
 
+{#--- Unions must be declared first because they can be members of structs #}
+{#--- Unions #}
+{%  for union in unions %}
+{%    include "wrapper_union_class_declaration.tmpl" %}
+{%- endfor %}
+
 {#--- NOTE: Non-inlined structs may have pointers to inlined structs, so we  #}
 {#---       need to fully define inlined structs ahead of the others.        #}
 
@@ -80,11 +86,6 @@ typedef mojo::StructPtr<{{union.name}}> {{union.name}}Ptr;
 {%    endif %}
 {%- endfor %}
 
-{#--- Unions #}
-{%  for union in unions %}
-{%    include "wrapper_union_class_declaration.tmpl" %}
-{%- endfor %}
-
 {#--- Interfaces -#}
 {%  for interface in interfaces %}
 {%    include "interface_declaration.tmpl" %}
@@ -110,18 +111,17 @@ typedef mojo::StructPtr<{{union.name}}> {{union.name}}Ptr;
 {%    include "interface_response_validator_declaration.tmpl" %}
 {%- endfor %}
 
-{%- import "serialization_macros.tmpl" as serialization_macros %}
 {#--- Struct Serialization Helpers -#}
 {%  if structs %}
 {%    for struct in structs %}
-{{      serialization_macros.declare_serialization(struct.name) }}
+{%      include "struct_serialization_declaration.tmpl" %}
 {%-   endfor %}
 {%- endif %}
 
 {#--- Union Serialization Helpers -#}
 {%  if unions %}
 {%    for union in unions %}
-{{      serialization_macros.declare_serialization(union.name) }}
+{%      include "union_serialization_declaration.tmpl" %}
 {%-   endfor %}
 {%- endif %}
 
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/serialization_macros.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/serialization_macros.tmpl
deleted file mode 100644
index 2be038c..0000000
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/serialization_macros.tmpl
+++ /dev/null
@@ -1,7 +0,0 @@
-{%- macro declare_serialization(name) %}
-size_t GetSerializedSize_(const {{name}}Ptr& input);
-void Serialize_({{name}}Ptr input, mojo::internal::Buffer* buffer,
-                internal::{{name}}_Data** output);
-void Deserialize_(internal::{{name}}_Data* input,
-                  {{name}}Ptr* output);
-{%- endmacro %}
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_definition.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_definition.tmpl
index 79a0bc4..32755cf 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_definition.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_definition.tmpl
@@ -11,17 +11,23 @@
 {%-   set kind = packed_field.field.kind %}
 {%-   set wrapper_type = kind|cpp_wrapper_type %}
 {%-   if not kind|is_nullable_kind %}
+{%-     if kind|is_union_kind %}
+  if (object->{{name}}.is_null()) {
+{%-     else %}
   if (!object->{{name}}.offset) {
+{%-     endif %}
     ReportValidationError(
         mojo::internal::VALIDATION_ERROR_UNEXPECTED_NULL_POINTER,
         "null {{name}} field in {{struct.name}} struct");
     return false;
   }
 {%-   endif %}
+{%-   if not kind|is_union_kind %}
   if (!mojo::internal::ValidateEncodedPointer(&object->{{name}}.offset)) {
     ReportValidationError(mojo::internal::VALIDATION_ERROR_ILLEGAL_POINTER);
     return false;
   }
+{%-   endif %}
 {%-   if kind|is_array_kind or kind|is_string_kind %}
   if (!{{wrapper_type}}::Data_::Validate<
           {{kind|get_array_validate_params|indent(10)}}>(
@@ -36,6 +42,9 @@
   if (!{{kind|get_name_for_kind}}::Data_::Validate(
           mojo::internal::DecodePointerRaw(&object->{{name}}.offset),
           bounds_checker)) {
+{%-   elif kind|is_union_kind %}
+  if (!{{kind|get_name_for_kind}}::Data_::Validate(
+          &object->{{name}}, bounds_checker, true)) {
 {%-   else %}
   if (!{{wrapper_type}}::Data_::Validate(
           mojo::internal::DecodePointerRaw(&object->{{name}}.offset),
@@ -139,7 +148,7 @@ void {{class_name}}::EncodePointersAndHandles(
     std::vector<mojo::Handle>* handles) {
   MOJO_CHECK(header_.version == {{struct.versions[-1].version}});
 {%- for pf in struct.packed.packed_fields_in_ordinal_order %}
-{%-   if pf.field.kind|is_object_kind %}
+{%-   if pf.field.kind|is_object_kind and not pf.field.kind|is_union_kind %}
   mojo::internal::Encode(&{{pf.field.name}}, handles);
 {%-   elif pf.field.kind|is_any_handle_kind %}
   mojo::internal::EncodeHandle(&{{pf.field.name}}, handles);
@@ -165,7 +174,9 @@ void {{class_name}}::DecodePointersAndHandles(
   if (header_.version < {{pf.min_version}})
     return;
 {%-     endif %}
-{%-     if kind|is_object_kind %}
+{%-     if kind|is_union_kind %}
+  // TODO(azani): Decode handles in union.
+{%-     elif kind|is_object_kind %}
   mojo::internal::Decode(&{{name}}, handles);
 {%-     else %}
   mojo::internal::DecodeHandle(&{{name}}, handles);
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl
index 03911b9..e8a625b 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_macros.tmpl
@@ -14,7 +14,11 @@
 {%- macro get_serialized_size(struct, input_field_pattern) -%}
   size_t size = sizeof(internal::{{struct.name}}_Data);
 {%-   for pf in struct.packed.packed_fields_in_ordinal_order if pf.field.kind|is_object_kind %}
+{%-     if pf.field.kind|is_union_kind %}
+  size += GetSerializedSize_({{input_field_pattern|format(pf.field.name)}}, true);
+{%-     else %}
   size += GetSerializedSize_({{input_field_pattern|format(pf.field.name)}});
+{%-     endif %}
 {%-   endfor %}
 {%- endmacro -%}
 
@@ -46,12 +50,19 @@
 {%-     elif kind|is_map_kind %}
   mojo::SerializeMap_<{{kind.value_kind|get_map_validate_params|indent(24)}}>(
       mojo::internal::Forward({{input_field}}), {{buffer}}, &{{output}}->{{name}}.ptr);
+{%-     elif kind|is_union_kind %}
+  internal::{{kind.name}}_Data* {{name}}_ptr = &{{output}}->{{name}};
+  SerializeUnion_(mojo::internal::Forward({{input_field}}), {{buffer}}, &{{name}}_ptr, true);
 {%-     else %}
   Serialize_(mojo::internal::Forward({{input_field}}), {{buffer}}, &{{output}}->{{name}}.ptr);
 {%-     endif %}
 {%-     if not kind|is_nullable_kind %}
   MOJO_INTERNAL_DLOG_SERIALIZATION_WARNING(
+{%-       if kind|is_union_kind %}
+      {{output}}->{{name}}.is_null(),
+{%-       else %}
       !{{output}}->{{name}}.ptr,
+{%-       endif %}
       mojo::internal::VALIDATION_ERROR_UNEXPECTED_NULL_POINTER,
       "null {{name}} in {{struct_display_name}}");
 {%-     endif %}
@@ -103,7 +114,11 @@
       break;
 {%-     endif %}
 {%-     if kind|is_object_kind %}
+{%-       if kind|is_union_kind %}
+    Deserialize_(&{{input}}->{{name}}, &{{output_field}});
+{%-       else %}
     Deserialize_({{input}}->{{name}}.ptr, &{{output_field}});
+{%-       endif %}
 {%-     elif kind|is_interface_kind or kind|is_interface_request_kind %}
     {{output_field}}.Bind(mojo::MakeScopedHandle(mojo::internal::FetchAndReset(&{{input}}->{{name}})));
 {%-     elif kind|is_any_handle_kind %}
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_declaration.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_declaration.tmpl
new file mode 100644
index 0000000..604be86
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/struct_serialization_declaration.tmpl
@@ -0,0 +1,5 @@
+size_t GetSerializedSize_(const {{struct.name}}Ptr& input);
+void Serialize_({{struct.name}}Ptr input, mojo::internal::Buffer* buffer,
+                internal::{{struct.name}}_Data** output);
+void Deserialize_(internal::{{struct.name}}_Data* input,
+                  {{struct.name}}Ptr* output);
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_declaration.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_declaration.tmpl
index 6e6fe95..bc77c11 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_declaration.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_declaration.tmpl
@@ -4,10 +4,22 @@
 
 class {{class_name}} {
  public:
+  // Used to identify Mojom Union Data Classes.
+  typedef void MojomUnionDataType;
   static {{class_name}}* New(mojo::internal::Buffer* buf);
+  {{class_name}}();
+  // Do nothing in the destructor since it won't be called.
+  ~{{class_name}}() {}
 
   static bool Validate(const void* data,
-                       mojo::internal::BoundsChecker* bounds_checker);
+                       mojo::internal::BoundsChecker* bounds_checker,
+                       bool inlined);
+
+  bool is_null() const {
+    return size == 0;
+  }
+
+  void set_null();
 
   enum class {{enum_name}} : uint32_t {
 {%  for field in union.fields %}
@@ -33,16 +45,12 @@ class {{class_name}} {
     uint64_t unknown;
   };
 
-  uint32_t reserved;
+  uint32_t size;
   {{enum_name}} tag;
   Union_ data;
 
   void EncodePointersAndHandles(std::vector<mojo::Handle>* handles);
   void DecodePointersAndHandles(std::vector<mojo::Handle>* handles);
- 
- private:
-  {{class_name}}();
-  ~{{class_name}}() = delete;
 };
 static_assert(sizeof({{class_name}}) == 16,
               "Bad sizeof({{class_name}})");
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_definition.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_definition.tmpl
index c9ea5d0..23e5cfd 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_definition.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_definition.tmpl
@@ -9,7 +9,8 @@
 
 // static
 bool {{class_name}}::Validate(const void* data,
-                              mojo::internal::BoundsChecker* bounds_checker) {
+                              mojo::internal::BoundsChecker* bounds_checker,
+                              bool inlined) {
   if (!data) {
     return true;
   }
@@ -19,7 +20,10 @@ bool {{class_name}}::Validate(const void* data,
     return false;
   }
 
-  if (!bounds_checker->ClaimMemory(data, sizeof({{class_name}}))) {
+  // If the union is inlined in another structure its memory was already claimed.
+  // This ONLY applies to the union itself, NOT anything which the union points
+  // to.
+  if (!inlined && !bounds_checker->ClaimMemory(data, sizeof({{class_name}}))) {
     ReportValidationError(
         mojo::internal::VALIDATION_ERROR_ILLEGAL_MEMORY_RANGE);
     return false;
@@ -40,6 +44,12 @@ bool {{class_name}}::Validate(const void* data,
   }
 }
 
+void {{class_name}}::set_null() {
+  size = 0U;
+  tag = static_cast<{{enum_name}}>(0);
+  data.unknown = 0U;
+}
+
 {{class_name}}::{{class_name}}() {
 }
 
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_declaration.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_declaration.tmpl
new file mode 100644
index 0000000..404eb83
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_declaration.tmpl
@@ -0,0 +1,5 @@
+size_t GetSerializedSize_(const {{union.name}}Ptr& input, bool inlined);
+void SerializeUnion_({{union.name}}Ptr input, mojo::internal::Buffer* buffer,
+                     internal::{{union.name}}_Data** output, bool inlined);
+void Deserialize_(internal::{{union.name}}_Data* input,
+                  {{union.name}}Ptr* output);
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl
index 8b82f7f..f928eba 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/union_serialization_definition.tmpl
@@ -1,8 +1,12 @@
-size_t GetSerializedSize_(const {{union.name}}Ptr& input) {
+size_t GetSerializedSize_(const {{union.name}}Ptr& input, bool inlined) {
+  size_t size = 0U;
+  if (!inlined) {
+    size += sizeof(internal::{{union.name}}_Data);
+  }
+
   if (!input)
-    return 0;
+    return size;
 
-  size_t size = sizeof(internal::{{union.name}}_Data);
   switch (input->which()) {
 {%  for field in union.fields %}
 {%    if field.kind|is_string_kind %}
@@ -17,14 +21,17 @@ size_t GetSerializedSize_(const {{union.name}}Ptr& input) {
   return size;
 }
 
-
-void Serialize_({{union.name}}Ptr input, mojo::internal::Buffer* buf,
-                internal::{{union.name}}_Data** output) {
+void SerializeUnion_({{union.name}}Ptr input, mojo::internal::Buffer* buf,
+                     internal::{{union.name}}_Data** output, bool inlined) {
+  internal::{{union.name}}_Data* result = *output;
   if (input) {
+    if (!inlined) {
+      result = internal::{{union.name}}_Data::New(buf);
+    }
     mojo::internal::UnionAccessor<{{union.name}}> input_acc(input.get());
-    internal::{{union.name}}_Data* result =
-        internal::{{union.name}}_Data::New(buf);
     // TODO(azani): Handle unknown and objects.
+    // Set the not-null flag.
+    result->size = 16;
     result->tag = input->which();
     switch (input->which()) {
 {%  for field in union.fields %}
@@ -38,15 +45,17 @@ void Serialize_({{union.name}}Ptr input, mojo::internal::Buffer* buf,
         break;
 {%- endfor %}
     }
-    *output = result;
+  } else if (inlined) {
+    result->set_null();
   } else {
-    *output = nullptr;
+    result = nullptr;
   }
+  *output = result;
 }
 
 void Deserialize_(internal::{{union.name}}_Data* input,
                   {{union.name}}Ptr* output) {
-  if (input) {
+  if (input && !input->is_null()) {
     {{union.name}}Ptr result({{union.name}}::New());
     mojo::internal::UnionAccessor<{{union.name}}> result_acc(result.get());
     switch (input->tag) {
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/wrapper_class_definition.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/wrapper_class_definition.tmpl
index da93e07..c171aa3 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/wrapper_class_definition.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/cpp_templates/wrapper_class_definition.tmpl
@@ -18,7 +18,7 @@
 {{struct.name}}Ptr {{struct.name}}::Clone() const {
   {{struct.name}}Ptr rv(New());
 {%-   for field in struct.fields %}
-{%-     if field.kind|is_struct_kind or field.kind|is_array_kind or field.kind|is_map_kind %}
+{%-     if field.kind|is_object_kind and not field.kind|is_string_kind %}
   rv->{{field.name}} = {{field.name}}.Clone();
 {%-     else %}
   rv->{{field.name}} = {{field.name}};
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/dart_templates/module.lib.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/dart_templates/module.lib.tmpl
index 21b643e..d6b869e 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/dart_templates/module.lib.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/dart_templates/module.lib.tmpl
@@ -10,7 +10,7 @@ import 'package:mojo/public/dart/bindings.dart' as bindings;
 import 'package:mojo/public/dart/core.dart' as core;
 
 {%- for import in imports %}
-import 'package:{{import.module.path}}.dart' as {{import.unique_name}};
+import 'package:{{import.rebased_path}}.dart' as {{import.unique_name}};
 {%- endfor %}
 
 {%- include "module_definition.tmpl" %}
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/dart_templates/struct_definition.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/dart_templates/struct_definition.tmpl
index 4d3f54d..6d9b653 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/dart_templates/struct_definition.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/dart_templates/struct_definition.tmpl
@@ -74,9 +74,11 @@ if (decoder{{level+1}} == null) {
 
 {%- macro struct_def(struct) %}
 class {{struct|name}} extends bindings.Struct {
-  static const int kStructSize = {{struct.versions[-1].num_bytes}};
-  static const bindings.StructDataHeader kDefaultStructInfo =
-      const bindings.StructDataHeader(kStructSize, {{struct.versions[-1].version}});
+  static const List<bindings.StructDataHeader> kVersions = const [
+{%- for version in struct.versions %}
+    const bindings.StructDataHeader({{version.num_bytes}}, {{version.version}}){% if not loop.last %},{% endif %}
+{%- endfor %}
+  ];
 
 {#--- Enums #}
 {%- from "enum_definition.tmpl" import enum_def %}
@@ -95,7 +97,7 @@ class {{struct|name}} extends bindings.Struct {
   {{packed_field.field.kind|dart_type}} {{packed_field.field|name}} = {{packed_field.field|default_value}};
 {%- endfor %}
 
-  {{struct|name}}() : super(kStructSize);
+  {{struct|name}}() : super(kVersions.last.size);
 
   static {{struct|name}} deserialize(bindings.Message message) {
     return decode(new bindings.Decoder(message));
@@ -108,14 +110,24 @@ class {{struct|name}} extends bindings.Struct {
     {{struct|name}} result = new {{struct|name}}();
 
     var mainDataHeader = decoder0.decodeStructDataHeader();
-    if ((mainDataHeader.size < kStructSize) ||
-        (mainDataHeader.version < {{struct.versions[-1].version}})) {
-      throw new bindings.MojoCodecError('Malformed header');
+    if (mainDataHeader.version <= kVersions.last.version) {
+      // Scan in reverse order to optimize for more recent versions.
+      for (int i = kVersions.length - 1; i >= 0; --i) {
+        if (mainDataHeader.version >= kVersions[i].version) {
+          if (mainDataHeader.size != kVersions[i].size)
+            throw new bindings.MojoCodecError(
+                'Header doesn\'t correspond to any known version.');
+        }
+      }
+    } else if (mainDataHeader.size < kVersions.last.size) {
+      throw new bindings.MojoCodecError(
+        'Message newer than the last known version cannot be shorter than '
+        'required by the last known version.');
     }
 
 {%- for byte in struct.bytes %}
 {%-   for packed_field in byte.packed_fields %}
-    {
+    if (mainDataHeader.version >= {{packed_field.min_version}}) {
       {{decode('result.' ~ packed_field.field|name, packed_field.field.kind, 8+packed_field.offset, packed_field.bit)|indent(6)}}
     }
 {%-   endfor %}
@@ -125,9 +137,9 @@ class {{struct|name}} extends bindings.Struct {
 
   void encode(bindings.Encoder encoder) {
 {%- if not struct.bytes %}
-    encoder.getStructEncoderAtOffset(kDefaultStructInfo);
+    encoder.getStructEncoderAtOffset(kVersions.last);
 {%- else %}
-    var encoder0 = encoder.getStructEncoderAtOffset(kDefaultStructInfo);
+    var encoder0 = encoder.getStructEncoderAtOffset(kVersions.last);
 {%- endif %}
 {%- for byte in struct.bytes %}
 {%-   for packed_field in byte.packed_fields %}
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/go_templates/interface.tmpl b/third_party/mojo/src/mojo/public/tools/bindings/generators/go_templates/interface.tmpl
index c96441e..25435e3 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/go_templates/interface.tmpl
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/go_templates/interface.tmpl
@@ -42,9 +42,37 @@ type {{interface|name}} interface {
 {% endfor %}
 }
 
+var {{interface|name(False)}}_Name = "{{interface.module.namespace|replace(".","::")}}::{{interface.name}}"
+
 type {{interface|name}}Request bindings.InterfaceRequest
+
+func (r *{{interface|name}}Request) Name() string {
+	return {{interface|name(False)}}_Name
+}
+
 type {{interface|name}}Pointer bindings.InterfacePointer
 
+func (p *{{interface|name}}Pointer) Name() string {
+	return {{interface|name(False)}}_Name
+}
+
+type {{interface|name}}ServiceFactory struct{
+	Delegate {{interface|name}}Factory
+}
+
+type {{interface|name}}Factory interface {
+	Create(request {{interface|name}}Request)
+}
+
+func (f *{{interface|name}}ServiceFactory) Name() string {
+	return {{interface|name(False)}}_Name
+}
+
+func (f *{{interface|name}}ServiceFactory) Create(messagePipe system.MessagePipeHandle) {
+	request := {{interface|name}}Request{bindings.NewMessagePipeHandleOwner(messagePipe)}
+	f.Delegate.Create(request)
+}
+
 // CreateMessagePipeFor{{interface|name}} creates a message pipe for use with the
 // {{interface|name}} interface with a {{interface|name}}Request on one end and a {{interface|name}}Pointer on the other.
 func CreateMessagePipeFor{{interface|name}}() ({{interface|name}}Request, {{interface|name}}Pointer) {
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_cpp_generator.py b/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
index 8b7e219..f38aecb 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_cpp_generator.py
@@ -75,6 +75,8 @@ def GetCppType(kind):
       GetCppType(kind.key_kind), GetCppType(kind.value_kind))
   if mojom.IsStructKind(kind):
     return "%s_Data*" % GetNameForKind(kind, internal=True)
+  if mojom.IsUnionKind(kind):
+    return "%s_Data" % GetNameForKind(kind, internal=True)
   if mojom.IsInterfaceKind(kind) or mojom.IsInterfaceRequestKind(kind):
     return "mojo::MessagePipeHandle"
   if mojom.IsEnumKind(kind):
@@ -91,7 +93,7 @@ def GetCppPodType(kind):
 def GetCppArrayArgWrapperType(kind):
   if mojom.IsEnumKind(kind):
     return GetNameForKind(kind)
-  if mojom.IsStructKind(kind):
+  if mojom.IsStructKind(kind) or mojom.IsUnionKind(kind):
     return "%sPtr" % GetNameForKind(kind)
   if mojom.IsArrayKind(kind):
     return "mojo::Array<%s> " % GetCppArrayArgWrapperType(kind.kind)
@@ -147,7 +149,7 @@ def GetCppResultWrapperType(kind):
 def GetCppWrapperType(kind):
   if mojom.IsEnumKind(kind):
     return GetNameForKind(kind)
-  if mojom.IsStructKind(kind):
+  if mojom.IsStructKind(kind) or mojom.IsUnionKind(kind):
     return "%sPtr" % GetNameForKind(kind)
   if mojom.IsArrayKind(kind):
     return "mojo::Array<%s>" % GetCppArrayArgWrapperType(kind.kind)
@@ -206,6 +208,8 @@ def GetCppFieldType(kind):
   if mojom.IsStructKind(kind):
     return ("mojo::internal::StructPointer<%s_Data>" %
         GetNameForKind(kind, internal=True))
+  if mojom.IsUnionKind(kind):
+    return "%s_Data" % GetNameForKind(kind, internal=True)
   if mojom.IsArrayKind(kind):
     return "mojo::internal::ArrayPointer<%s>" % GetCppType(kind.kind)
   if mojom.IsMapKind(kind):
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 2b562f2..fb1cfd4 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
@@ -4,6 +4,7 @@
 
 """Generates dart source files from a mojom.Module."""
 
+import os
 import re
 
 import mojom.generate.generator as generator
@@ -373,10 +374,10 @@ class Generator(generator.Generator):
     'struct_from_method': generator.GetStructFromMethod,
   }
 
-  def GetParameters(self):
+  def GetParameters(self, args):
     return {
       "namespace": self.module.namespace,
-      "imports": self.GetImports(),
+      "imports": self.GetImports(args),
       "kinds": self.module.kinds,
       "enums": self.module.enums,
       "module": self.module,
@@ -387,14 +388,20 @@ class Generator(generator.Generator):
     }
 
   @UseJinja("dart_templates/module.lib.tmpl", filters=dart_filters)
-  def GenerateLibModule(self):
-    return self.GetParameters()
+  def GenerateLibModule(self, args):
+    return self.GetParameters(args)
 
   def GenerateFiles(self, args):
-    self.Write(self.GenerateLibModule(),
+    self.Write(self.GenerateLibModule(args),
         self.MatchMojomFilePath("%s.dart" % self.module.name))
 
-  def GetImports(self):
+  def GetImports(self, args):
+    mojo_root_arg = next(
+        (x for x in args if x.startswith("--dart_mojo_root")), "")
+    (_, _, mojo_root_path) = mojo_root_arg.partition("=")
+    if not mojo_root_path.startswith("//"):
+      raise Exception("Malformed mojo SDK root: " + mojo_root_path)
+    mojo_root_path = mojo_root_path[2:]  # strip //
     used_names = set()
     for each_import in self.module.imports:
       simple_name = each_import["module_name"].split(".")[0]
@@ -410,6 +417,16 @@ class Generator(generator.Generator):
       used_names.add(unique_name)
       each_import["unique_name"] = unique_name + '_mojom'
       counter += 1
+
+      # At this point, a module's path is reletive to the root of the repo.
+      # However, imports of libraries from the Mojo SDK are always reletive to
+      # root of the Mojo SDK, which may be different from the root of the repo.
+      # This code uses the --dart_mojo_root argument to ensure that Mojo SDK
+      # imports are reletive to the Mojo SDK root.
+      path = each_import['module'].path
+      if os.path.commonprefix([mojo_root_path, path]) == mojo_root_path:
+        path = os.path.relpath(path, mojo_root_path)
+      each_import["rebased_path"] = path
     return self.module.imports
 
   def GetImportedInterfaces(self):
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_go_generator.py b/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_go_generator.py
index 9273186..f841b848 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_go_generator.py
+++ b/third_party/mojo/src/mojo/public/tools/bindings/generators/mojom_go_generator.py
@@ -263,6 +263,8 @@ def GetImports(module):
   if len(all_structs) > 0 or len(module.interfaces) > 0:
     _imports['fmt'] = 'fmt'
     _imports['mojo/public/go/bindings'] = 'bindings'
+  if len(module.interfaces) > 0:
+    _imports['mojo/public/go/system'] = 'system'
   if len(all_structs) > 0:
     _imports['sort'] = 'sort'
 
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/mojom.gni b/third_party/mojo/src/mojo/public/tools/bindings/mojom.gni
index dd68501..6c03ea6 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/mojom.gni
+++ b/third_party/mojo/src/mojo/public/tools/bindings/mojom.gni
@@ -61,20 +61,21 @@ template("mojom") {
       "$generator_root/generators/cpp_templates/interface_request_validator_declaration.tmpl",
       "$generator_root/generators/cpp_templates/interface_response_validator_declaration.tmpl",
       "$generator_root/generators/cpp_templates/interface_stub_declaration.tmpl",
+      "$generator_root/generators/cpp_templates/module-internal.h.tmpl",
       "$generator_root/generators/cpp_templates/module.cc.tmpl",
       "$generator_root/generators/cpp_templates/module.h.tmpl",
-      "$generator_root/generators/cpp_templates/module-internal.h.tmpl",
-      "$generator_root/generators/cpp_templates/serialization_macros.tmpl",
       "$generator_root/generators/cpp_templates/struct_declaration.tmpl",
       "$generator_root/generators/cpp_templates/struct_definition.tmpl",
-      "$generator_root/generators/cpp_templates/struct_serialization_definition.tmpl",
       "$generator_root/generators/cpp_templates/struct_macros.tmpl",
-      "$generator_root/generators/cpp_templates/wrapper_class_declaration.tmpl",
-      "$generator_root/generators/cpp_templates/wrapper_class_definition.tmpl",
+      "$generator_root/generators/cpp_templates/struct_serialization_declaration.tmpl",
+      "$generator_root/generators/cpp_templates/struct_serialization_definition.tmpl",
       "$generator_root/generators/cpp_templates/union_declaration.tmpl",
       "$generator_root/generators/cpp_templates/union_definition.tmpl",
+      "$generator_root/generators/cpp_templates/union_serialization_declaration.tmpl",
       "$generator_root/generators/cpp_templates/union_serialization_definition.tmpl",
       "$generator_root/generators/cpp_templates/validation_macros.tmpl",
+      "$generator_root/generators/cpp_templates/wrapper_class_declaration.tmpl",
+      "$generator_root/generators/cpp_templates/wrapper_class_definition.tmpl",
       "$generator_root/generators/cpp_templates/wrapper_union_class_declaration.tmpl",
       "$generator_root/generators/cpp_templates/wrapper_union_class_definition.tmpl",
       "$generator_root/generators/dart_templates/enum_definition.tmpl",
@@ -101,8 +102,8 @@ template("mojom") {
       "$generator_root/generators/js_templates/module.amd.tmpl",
       "$generator_root/generators/js_templates/module_definition.tmpl",
       "$generator_root/generators/js_templates/struct_definition.tmpl",
-      "$generator_root/generators/python_templates/module_macros.tmpl",
       "$generator_root/generators/python_templates/module.py.tmpl",
+      "$generator_root/generators/python_templates/module_macros.tmpl",
       "$generator_root/generators/mojom_cpp_generator.py",
       "$generator_root/generators/mojom_dart_generator.py",
       "$generator_root/generators/mojom_go_generator.py",
@@ -180,6 +181,7 @@ template("mojom") {
                 generator_js_outputs + generator_python_outputs
       args = [
         "{{source}}",
+        "--dart_mojo_root=${mojo_root}",
         "--use_bundled_pylibs",
         "-d",
         rebase_path("//", root_build_dir),
@@ -334,21 +336,21 @@ template("mojom") {
       output,
     ]
 
-    invoker_base_dir = ""
-    if (defined(invoker.base_dir)) {
-      invoker_base_dir =
-          rebase_path(invoker.base_dir, "$root_build_dir/../../", ".")
+    invoker_import_from = ""
+    if (defined(invoker.import_from)) {
+      invoker_import_from =
+          rebase_path(invoker.import_from, "$root_build_dir/../../", ".")
     }
 
-    rebase_base_dir =
-        rebase_path("$root_build_dir/gen/$invoker_base_dir", root_build_dir)
+    rebase_import_from =
+        rebase_path("$root_build_dir/gen/$invoker_import_from", root_build_dir)
     if (defined(invoker.sources)) {
       rebase_inputs = rebase_path(inputs, root_build_dir)
     }
     rebase_zip_inputs = rebase_path(zip_inputs, root_build_dir)
     rebase_output = rebase_path(output, root_build_dir)
     args = [
-      "--base-dir=$rebase_base_dir",
+      "--base-dir=$rebase_import_from",
       "--zip-inputs=$rebase_zip_inputs",
       "--output=$rebase_output",
     ]
diff --git a/third_party/mojo/src/mojo/public/tools/bindings/pylib/mojom/generate/pack.py b/third_party/mojo/src/mojo/public/tools/bindings/pylib/mojom/generate/pack.py
index 4e522c9..9c72cfa 100644
--- a/third_party/mojo/src/mojo/public/tools/bindings/pylib/mojom/generate/pack.py
+++ b/third_party/mojo/src/mojo/public/tools/bindings/pylib/mojom/generate/pack.py
@@ -45,6 +45,8 @@ class PackedField(object):
   def GetSizeForKind(cls, kind):
     if isinstance(kind, (mojom.Array, mojom.Map, mojom.Struct)):
       return 8
+    if isinstance(kind, mojom.Union):
+      return 16
     if (isinstance(kind, mojom.Interface) or
         isinstance(kind, mojom.InterfaceRequest)):
       kind = mojom.MSGPIPE
diff --git a/third_party/mojo/src/mojo/public/tools/dart_analyze.py b/third_party/mojo/src/mojo/public/tools/dart_analyze.py
index c200783..f26ddbf 100755
--- a/third_party/mojo/src/mojo/public/tools/dart_analyze.py
+++ b/third_party/mojo/src/mojo/public/tools/dart_analyze.py
@@ -20,6 +20,9 @@ import tempfile
 import zipfile
 
 _ANALYZING_PATTERN = re.compile(r'^Analyzing \[')
+_NO_ISSUES_FOUND_PATTERN = re.compile(r'^No issues found')
+_PART_WARNINGS_PATTERN = re.compile(
+  r'.*is a part and can not|^Only libraries can be analyzed')
 _ERRORS_AND_WARNINGS_PATTERN = re.compile(
   r'^[0-9]+ errors? and [0-9]+ warnings? found.')
 _ERRORS_PATTERN = re.compile(r'^([0-9]+|No) (error|warning|issue)s? found.')
@@ -59,6 +62,8 @@ def main(args):
       raw_lines.pop()
       filtered_lines = [i for i in raw_lines if (
         not re.match(_ANALYZING_PATTERN, i) and
+        not re.match(_NO_ISSUES_FOUND_PATTERN, i) and
+        not re.match(_PART_WARNINGS_PATTERN, i) and
         not re.match(_ERRORS_AND_WARNINGS_PATTERN, i) and
         not re.match(_ERRORS_PATTERN, i))]
       for line in filtered_lines:
diff --git a/third_party/mojo/src/mojo/public/tools/gn/zip.py b/third_party/mojo/src/mojo/public/tools/gn/zip.py
index 506eb9e..a73f801 100755
--- a/third_party/mojo/src/mojo/public/tools/gn/zip.py
+++ b/third_party/mojo/src/mojo/public/tools/gn/zip.py
@@ -15,7 +15,7 @@ import zipfile
 
 def DoZip(inputs, zip_inputs, output, base_dir):
   files = []
-  with zipfile.ZipFile(output, 'w') as outfile:
+  with zipfile.ZipFile(output, 'w', zipfile.ZIP_DEFLATED) as outfile:
     for f in inputs:
       file_name = os.path.relpath(f, base_dir)
       files.append(file_name)
diff --git a/third_party/mojo/src/mojo/public/tools/mojom_fetcher/mojom_fetcher.py b/third_party/mojo/src/mojo/public/tools/mojom_fetcher/mojom_fetcher.py
new file mode 100755
index 0000000..b0283e3
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/tools/mojom_fetcher/mojom_fetcher.py
@@ -0,0 +1,196 @@
+#!/usr/bin/env python
+# 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.
+
+"""Tool to manage external mojom interfaces."""
+
+import argparse
+import errno
+import logging
+import os
+import sys
+import urllib2
+
+# Local library
+sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                                "pylib"))
+# Bindings library
+sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                                "..", "bindings", "pylib"))
+# Requests library
+sys.path.insert(0, os.path.join(os.path.dirname(os.path.abspath(__file__)),
+                                "..", "..", "..", "..", "third_party",
+                                "requests", "src"))
+
+import requests
+
+from fetcher.repository import Repository
+from fetcher.dependency import Dependency
+from mojom.parse.parser import Parse, ParseError
+
+
+class UrlRewriterException(Exception):
+  """Exception when processing URL rewrite rules."""
+  pass
+
+class UrlRewriter(object):
+  """UrlRewriter rewrites URLs according to the provided mappings.
+
+  Note that mappings are not followed transitively. If mappings contains
+  {"a": "b", "b": "c"}, then UrlRewriter.rewrite("a") will return "b", not "c".
+  """
+
+  def __init__(self, mappings):
+    self._mappings = mappings
+    for target in self._mappings.values():
+      for source in self._mappings.keys():
+        if source in target or target in source:
+          raise UrlRewriterException(
+              "%s and %s share a common subpath" % (source, target))
+
+  def rewrite(self, path):
+    for origin, destination in self._mappings.items():
+      if path.startswith(origin):
+        return destination + path[len(origin):]
+    return path
+
+
+class MojomFetcher(object):
+  def __init__(self, repository, url_rewriter):
+    self._repository = repository
+    self._url_rewriter = url_rewriter
+
+  def _requests_get(self, url):
+    return requests.get(url, verify=True)
+
+  def _os_makedirs(self, dirs):
+    try:
+      os.makedirs(dirs)
+    except OSError as e:
+      # The directory may already exist, we don't care.
+      if e.errno != errno.EEXIST:
+        raise
+
+  def _open(self, f, mode="r"):
+    return open(f, mode)
+
+  def _download_dependencies(self, dependencies):
+    """Takes the list of mojom dependencies and download the external ones.
+    Returns the number of successfully downloaded dependencies."""
+
+    downloaded = 0
+    for dep in dependencies:
+      if self._maybe_download_dep(dep):
+        downloaded += 1
+    return downloaded
+
+  def _maybe_download_dep(self, dep):
+    if not dep.maybe_is_a_url():
+      return False
+
+    for candidate in dep.generate_candidate_urls():
+      url = self._url_rewriter.rewrite(candidate)
+      response = self._requests_get("https://" + url)
+      if not response.ok:
+        # If we get an error, it just mean that this candidate URL is not
+        # correct. We must try the other ones before giving up.
+        logging.debug("Error while downloading %s (%s)", candidate, url)
+        continue
+      # This is an external dependency
+      directory = os.path.dirname(candidate)
+      full_directory = os.path.join(self._repository.get_external_directory(),
+                                    directory)
+      try:
+        self._os_makedirs(full_directory)
+      except OSError as e:
+        # The directory may already exist, we don't care.
+        if e.errno != errno.EEXIST:
+          raise
+      with self._open(os.path.join(self._repository.get_external_directory(),
+                             candidate), "w") as f:
+        data = response.content
+        try:
+          Parse(data, candidate)
+        except ParseError:
+          logging.warn("File at %s is not a mojom", url)
+          break
+        f.write(data)
+      return True
+    return False
+
+  def discover(self):
+    """Discover missing .mojom dependencies and download them."""
+    while True:
+      missing_deps = self._repository.get_missing_dependencies()
+      downloaded = self._download_dependencies(missing_deps)
+      if downloaded == 0:
+        return 0
+
+  def get(self, dep):
+    dependency = Dependency(self._repository, ".", dep)
+    downloaded = self._download_dependencies([dependency])
+    if downloaded != 0:
+      return self.discover()
+    else:
+      return -1
+
+  def update(self):
+    dependencies = [Dependency(self._repository, ".", f)
+                    for f in self._repository.get_external_urls()]
+    # TODO(etiennej): We may want to suggest to the user to delete
+    # un-downloadable dependencies.
+    downloaded = self._download_dependencies(dependencies)
+    if downloaded != 0:
+      return self.discover()
+    else:
+      return -1
+
+def _main(args):
+  if args.prefix_rewrite:
+    rewrite_rules = dict([x.split(':', 1) for x in args.prefix_rewrite])
+  else:
+    rewrite_rules = {}
+  rewriter = UrlRewriter(rewrite_rules)
+  repository_path = os.path.abspath(args.repository_path)
+  repository = Repository(repository_path, args.external_dir)
+  fetcher = MojomFetcher(repository, rewriter)
+  if args.action == 'discover':
+    return fetcher.discover()
+  elif args.action == 'get':
+    return fetcher.get(args.url)
+  elif args.action == 'update':
+    return fetcher.update()
+  else:
+    logging.error("No matching action %s", args.action[0])
+    return -1
+
+def main():
+  logging.basicConfig(level=logging.ERROR)
+  parser = argparse.ArgumentParser(description='Download mojom dependencies.')
+  parser.add_argument('--repository-path', type=str, action='store',
+                      default='.', help='The path to the client repository.')
+  parser.add_argument('--external-dir', type=str, action='store',
+                      default='external',
+                      help='Directory for external interfaces')
+  parser.add_argument('--prefix-rewrite', type=str, action='append',
+                      help='If present, "origin:destination" pairs. "origin" '
+                      'prefixes will be rewritten as "destination". May be '
+                      'used several times. Rewrites are not transitive.')
+
+  subparsers = parser.add_subparsers(dest='action', help='action')
+  parser_get = subparsers.add_parser(
+      'get', help='Get the specified URL and all its transitive dependencies')
+  parser_get.add_argument('url', type=str, nargs=1,
+                      help='URL to download for get action')
+  subparsers.add_parser(
+      'discover',
+      help='Recursively discover and download new external dependencies')
+  subparsers.add_parser('update', help='Update all external dependencies')
+
+  args = parser.parse_args()
+  return _main(args)
+
+
+if __name__ == '__main__':
+  sys.exit(main())
diff --git a/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/__init__.py b/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/__init__.py
diff --git a/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/dependency.py b/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/dependency.py
new file mode 100644
index 0000000..a4716e4
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/dependency.py
@@ -0,0 +1,97 @@
+# 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.
+
+import os
+
+
+class Dependency(object):
+  """Dependency represents an import request from one mojom file to another.
+  """
+  def __init__(self, repository, importer, imported):
+    self._repository = repository
+    self._importer_filename = os.path.normpath(importer)
+    self._imported_filename = os.path.normpath(imported)
+
+  def __str__(self):
+    return str(self.__dict__)
+
+  def __eq__(self, other):
+    return self.__dict__ == other.__dict__
+
+  def get_importer(self):
+    """Returns the name and full path of the file doing the import."""
+    return self._importer_filename
+
+  def get_imported(self):
+    """Returns the imported file (filename and path)."""
+    return self._imported_filename
+
+  def is_sdk_dep(self):
+    """Returns whether this dependency is from the mojo SDK."""
+    return (self._imported_filename.startswith("mojo/public/") or
+            self._imported_filename.startswith("//mojo/public/"))
+
+  def _is_in_external(self):
+    """Returns whether this dependency is under the external directory."""
+    common = os.path.commonprefix((self._repository.get_external_directory(),
+                                   self._importer_filename))
+    return common == self._repository.get_external_directory()
+
+  def maybe_is_a_url(self):
+    """Returns whether this dependency may be pointing to a downloadable
+    ressource."""
+    if self._is_in_external() and not self.is_sdk_dep():
+      # External dependencies may refer to other dependencies by relative path,
+      # so they can always be URLs.
+      return True
+
+    base, _ = self._imported_filename.split(os.path.sep, 1)
+    if not '.' in base:
+      # There is no dot separator in the first part of the path; it cannot be a
+      # URL.
+      return False
+    return True
+
+  def generate_candidate_urls(self):
+    """Generates possible paths where to download this dependency. It is
+    expected that at most one of them should work."""
+    candidates = []
+
+    base, _ = self._imported_filename.split(os.path.sep, 1)
+    if '.' in base and not base.startswith('.'):
+      # This import may be an absolute URL path (without scheme).
+      candidates.append(self._imported_filename)
+
+    # External dependencies may refer to other dependencies by relative path.
+    if self._is_in_external():
+      directory = os.path.relpath(os.path.dirname(self._importer_filename),
+                                  self._repository.get_external_directory())
+
+      # This is to handle the case where external dependencies use
+      # imports relative to a directory upper in the directory structure. As we
+      # don't know which directory, we need to go through all of them.
+      while len(directory) > 0:
+        candidates.append(os.path.join(directory, self._imported_filename))
+        directory = os.path.dirname(directory)
+    return candidates
+
+  def get_search_path_for_dependency(self):
+    """Return all possible search paths for this dependency."""
+
+    # Root directory and external directory are always included.
+    search_paths = set([self._repository.get_repo_root_directory(),
+                        self._repository.get_external_directory()])
+    # Local import paths
+    search_paths.add(os.path.dirname(self._importer_filename))
+
+    if self._is_in_external():
+      directory = os.path.dirname(self._importer_filename)
+
+      # This is to handle the case where external dependencies use
+      # imports relative to a directory upper in the directory structure. As we
+      # don't know which directory, we need to go through all of them.
+      while self._repository.get_external_directory() in directory:
+        search_paths.add(directory)
+        directory = os.path.dirname(directory)
+    return search_paths
diff --git a/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/mojom_file.py b/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/mojom_file.py
new file mode 100644
index 0000000..ad8c969
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/mojom_file.py
@@ -0,0 +1,18 @@
+# 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.
+
+from fetcher.dependency import Dependency
+
+
+class MojomFile(object):
+  """Mojom represents an interface file at a given location in the
+  repository."""
+  def __init__(self, repository, name):
+    self.name = name
+    self._repository = repository
+    self.deps = []
+
+  def add_dependency(self, dependency):
+    """Declare a new dependency of this mojom."""
+    self.deps.append(Dependency(self._repository, self.name, dependency))
diff --git a/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/repository.py b/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/repository.py
new file mode 100644
index 0000000..dde99b2
--- /dev/null
+++ b/third_party/mojo/src/mojo/public/tools/mojom_fetcher/pylib/fetcher/repository.py
@@ -0,0 +1,88 @@
+# 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.
+
+import os
+
+from fetcher.dependency import Dependency
+from mojom.parse.parser import Parse
+
+
+class Repository(object):
+  """Repository represents a code repository on the local disc."""
+  def __init__(self, root_dir, external_dir):
+    """root_dir represents the root of the repository;
+    external_dir is the relative path of the external directory within the
+    repository (so, relative to root_dir)
+    """
+    self._root_dir = os.path.normpath(root_dir)
+    self._external_dir = external_dir
+
+  def get_repo_root_directory(self):
+    return self._root_dir
+
+  def get_external_directory(self):
+    return os.path.join(self._root_dir, self._external_dir)
+
+  def _os_walk(self, root_directory):
+    # This method is included for dependency injection
+    return os.walk(root_directory)
+
+  def _open(self, filename):
+    # This method is included for dependency injection
+    return open(filename)
+
+  def _get_all_mojom_in_directory(self, root_directory):
+    mojoms = []
+    for dirname, _, files in self._os_walk(root_directory):
+      for f in files:
+        if f.endswith(".mojom"):
+          mojoms.append(os.path.join(dirname,f))
+    return mojoms
+
+  def _resolve_dependencies(self, dependencies, mojoms):
+    """Resolve dependencies between discovered mojoms, so we know which are the
+    missing ones."""
+    missing = []
+    for dependency in dependencies:
+      found = False
+      for search_path in dependency.get_search_path_for_dependency():
+        if os.path.normpath(
+            os.path.join(search_path,
+                         dependency.get_imported())) in mojoms:
+          found = True
+          break
+      if not found:
+        missing.append(dependency)
+    return missing
+
+  def get_missing_dependencies(self):
+    """get_missing_dependencies returns a set of dependencies that are required
+    by mojoms in this repository but not available.
+    """
+    # Update the list of available mojoms in this repository.
+    mojoms = set(self._get_all_mojom_in_directory(self._root_dir))
+
+    # Find all declared dependencies
+    needed_deps = set([])
+    for mojom in mojoms:
+      with self._open(mojom) as f:
+        source = f.read()
+        tree = Parse(source, mojom)
+        for dep in tree.import_list:
+          needed_deps.add(Dependency(self, dep.filename, dep.import_filename))
+
+    missing_deps = self._resolve_dependencies(needed_deps, mojoms)
+
+    return missing_deps
+
+  def get_external_urls(self):
+    """Get all external mojom files in this repository, by urls (without
+    scheme)."""
+    mojoms = set(self._get_all_mojom_in_directory(
+        self.get_external_directory()))
+    urls = []
+    for mojom in mojoms:
+      urls.append(os.path.relpath(mojom, self.get_external_directory()))
+    return urls
+
diff --git a/third_party/mojo_services/src/accessibility/public/interfaces/BUILD.gn b/third_party/mojo_services/src/accessibility/public/interfaces/BUILD.gn
index 2b29c1a..f2c1ba8 100644
--- a/third_party/mojo_services/src/accessibility/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/accessibility/public/interfaces/BUILD.gn
@@ -15,4 +15,6 @@ mojom("interfaces") {
   deps = [
     "../../../geometry/public/interfaces",
   ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/clipboard/public/interfaces/BUILD.gn b/third_party/mojo_services/src/clipboard/public/interfaces/BUILD.gn
index 16fe33b..4edbf63 100644
--- a/third_party/mojo_services/src/clipboard/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/clipboard/public/interfaces/BUILD.gn
@@ -9,4 +9,6 @@ mojom("interfaces") {
   sources = [
     "clipboard.mojom",
   ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/content_handler/public/interfaces/BUILD.gn b/third_party/mojo_services/src/content_handler/public/interfaces/BUILD.gn
index c58507a..ad1bb9a 100644
--- a/third_party/mojo_services/src/content_handler/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/content_handler/public/interfaces/BUILD.gn
@@ -23,4 +23,6 @@ mojom("interfaces") {
   ]
 
   mojo_sdk_deps = [ "mojo/public/interfaces/application" ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/geometry/public/interfaces/BUILD.gn b/third_party/mojo_services/src/geometry/public/interfaces/BUILD.gn
index 9047ee2..217eb27 100644
--- a/third_party/mojo_services/src/geometry/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/geometry/public/interfaces/BUILD.gn
@@ -9,4 +9,6 @@ mojom("interfaces") {
   sources = [
     "geometry.mojom",
   ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/gpu/public/interfaces/BUILD.gn b/third_party/mojo_services/src/gpu/public/interfaces/BUILD.gn
index ec061df..b782146 100644
--- a/third_party/mojo_services/src/gpu/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/gpu/public/interfaces/BUILD.gn
@@ -19,4 +19,6 @@ mojom("interfaces") {
   deps = [
     "../../../geometry/public/interfaces",
   ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/http_server/public/interfaces/BUILD.gn b/third_party/mojo_services/src/http_server/public/interfaces/BUILD.gn
index 79aa6a6..a02039e 100644
--- a/third_party/mojo_services/src/http_server/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/http_server/public/interfaces/BUILD.gn
@@ -24,4 +24,6 @@ mojom("interfaces") {
   deps = [
     "$mojo_network_service_root/network/public/interfaces",
   ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/input_events/public/interfaces/BUILD.gn b/third_party/mojo_services/src/input_events/public/interfaces/BUILD.gn
index 5ef09eb..5f0f22d 100644
--- a/third_party/mojo_services/src/input_events/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/input_events/public/interfaces/BUILD.gn
@@ -17,4 +17,6 @@ mojom("interfaces") {
   deps = [
     "../../../geometry/public/interfaces",
   ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/input_events/public/interfaces/input_events.mojom b/third_party/mojo_services/src/input_events/public/interfaces/input_events.mojom
index 0086265..9fa36303 100644
--- a/third_party/mojo_services/src/input_events/public/interfaces/input_events.mojom
+++ b/third_party/mojo_services/src/input_events/public/interfaces/input_events.mojom
@@ -70,6 +70,8 @@ struct Event {
   EventType action;
   // TODO(sky): parts of this should move to PointerData.
   EventFlags flags;
+  // Time the event was delivered. The time is in milliseconds and corresponds
+  // to the uptime of the machine.
   int64 time_stamp;
   KeyData? key_data;
   PointerData? pointer_data;
diff --git a/third_party/mojo_services/src/native_viewport/public/interfaces/BUILD.gn b/third_party/mojo_services/src/native_viewport/public/interfaces/BUILD.gn
index 86ff870..5603e17 100644
--- a/third_party/mojo_services/src/native_viewport/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/native_viewport/public/interfaces/BUILD.gn
@@ -18,4 +18,6 @@ mojom("interfaces") {
     "../../../input_events/public/interfaces",
     "../../../surfaces/public/interfaces:surface_id",
   ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/navigation/public/interfaces/BUILD.gn b/third_party/mojo_services/src/navigation/public/interfaces/BUILD.gn
index 19b9f8a..61158f3 100644
--- a/third_party/mojo_services/src/navigation/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/navigation/public/interfaces/BUILD.gn
@@ -21,4 +21,6 @@ mojom("interfaces") {
   deps = [
     "$mojo_network_service_root/network/public/interfaces",
   ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/surfaces/public/interfaces/BUILD.gn b/third_party/mojo_services/src/surfaces/public/interfaces/BUILD.gn
index 7902a7a..36c8707 100644
--- a/third_party/mojo_services/src/surfaces/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/surfaces/public/interfaces/BUILD.gn
@@ -20,10 +20,14 @@ mojom("interfaces") {
     "../../../gpu/public/interfaces",
     "../../../native_viewport/public/interfaces",
   ]
+
+  import_from = mojo_root
 }
 
 mojom("surface_id") {
   sources = [
     "surface_id.mojom",
   ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/view_manager/public/interfaces/BUILD.gn b/third_party/mojo_services/src/view_manager/public/interfaces/BUILD.gn
index 177066b..eff5f62 100644
--- a/third_party/mojo_services/src/view_manager/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/view_manager/public/interfaces/BUILD.gn
@@ -22,4 +22,6 @@ mojom("interfaces") {
     "../../../native_viewport/public/interfaces",
     "../../../surfaces/public/interfaces:surface_id",
   ]
+
+  import_from = mojo_root
 }
diff --git a/third_party/mojo_services/src/window_manager/public/interfaces/BUILD.gn b/third_party/mojo_services/src/window_manager/public/interfaces/BUILD.gn
index b97f069..3cf56dad 100644
--- a/third_party/mojo_services/src/window_manager/public/interfaces/BUILD.gn
+++ b/third_party/mojo_services/src/window_manager/public/interfaces/BUILD.gn
@@ -19,4 +19,6 @@ mojom("interfaces") {
     "../../../geometry/public/interfaces",
     "../../../input_events/public/interfaces",
   ]
+
+  import_from = mojo_root
 }