Hook up RendererMediaSessionManager with browser side

content/renderer/media/android/renderer_media_session_manager.h

Index: content/renderer/media/android/renderer_media_session_manager.h
diff --git a/content/renderer/media/android/renderer_media_session_manager.h b/content/renderer/media/android/renderer_media_session_manager.h
index f07b230c113f671884dc25c30d4b714c7bd0a258..831fe24e99544139bdf9068a7b8f4fe9c717c577 100644
--- a/content/renderer/media/android/renderer_media_session_manager.h
+++ b/content/renderer/media/android/renderer_media_session_manager.h
@@ -20,12 +20,24 @@ class CONTENT_EXPORT RendererMediaSessionManager : public RenderFrameObserver {
   RendererMediaSessionManager(RenderFrame* render_frame);
   ~RendererMediaSessionManager() override;
 
+  // RenderFrameObserver override.
+  bool OnMessageReceived(const IPC::Message& msg) override;
+
   int RegisterMediaSession(WebMediaSessionAndroid* session);
   void UnregisterMediaSession(int session_id);
 
+  void Activate(int session_id, int activation_id);
+  void Deactivate(int session_id, int deactivation_id);
+
+  void OnDidActivate(int session_id, int activation_id, bool success);
+  void OnDidDeactivate(int session_id, int deactivation_id);
+
  private:
   friend class WebMediaSessionTest;
 
+  // RenderFrameObserver override.
+  bool Send(IPC::Message* message) override;
+
   std::map<int, WebMediaSessionAndroid*> sessions_;
   int next_session_id_;