[MediaRouter] Update MR-2-Extension's PostMessage to return boolean.

chrome/browser/media/router/test_helper.h

 // 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.
 
 #ifndef CHROME_BROWSER_MEDIA_ROUTER_TEST_HELPER_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_TEST_HELPER_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 30 matching lines @@
   MockMojoMediaRouterService();
   ~MockMojoMediaRouterService() override;
 
   MOCK_METHOD3(CreateRoute,
                void(const mojo::String& source,
                     const mojo::String& sink_id,
                     const CreateRouteCallback& callback));
   MOCK_METHOD1(CloseRoute, void(const mojo::String& route_id));
   MOCK_METHOD1(StartObservingMediaSinks, void(const mojo::String& source));
   MOCK_METHOD1(StopObservingMediaSinks, void(const mojo::String& source));
-  MOCK_METHOD2(PostMessage,
+  MOCK_METHOD3(SendRouteMessage,
                void(const mojo::String& media_route_id,
-                    const mojo::String& message));
+                    const mojo::String& message,
+                    const SendRouteMessageCallback& callback));
   MOCK_METHOD1(ClearIssue, void(const mojo::String& issue_id));
   MOCK_METHOD0(StartObservingMediaRoutes, void());
   MOCK_METHOD0(StopObservingMediaRoutes, void());
 
  private:
   DISALLOW_COPY_AND_ASSIGN(MockMojoMediaRouterService);
 };
 
 class MockMediaSinksObserver : public MediaSinksObserver {
  public:
@@ skipping 18 matching lines @@
 
   MOCK_METHOD1(IsEventPageSuspended, bool(const std::string& extension_id));
   MOCK_METHOD2(WakeEventPage,
                bool(const std::string& extension_id,
                     const base::Callback<void(bool)>& callback));
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_TEST_HELPER_H_