Implement MediaSession on top of the WebMediaPlayerDelegate.

content/browser/media/android/browser_media_player_manager.h

Index: content/browser/media/android/browser_media_player_manager.h
diff --git a/content/browser/media/android/browser_media_player_manager.h b/content/browser/media/android/browser_media_player_manager.h
index 061878bd8d16c5d0cf519687520569e1d3458330..94c3209bbac5a485bf3f8f343d7a383ed48dd6fa 100644
--- a/content/browser/media/android/browser_media_player_manager.h
+++ b/content/browser/media/android/browser_media_player_manager.h
@@ -13,7 +13,6 @@
 #include "base/memory/scoped_vector.h"
 #include "base/time/time.h"
 #include "content/browser/android/content_video_view.h"
-#include "content/browser/media/android/media_session_observer.h"
 #include "content/common/content_export.h"
 #include "content/common/media/media_player_messages_enums_android.h"
 #include "ipc/ipc_message.h"
@@ -44,8 +43,7 @@ class WebContents;
 // MediaPlayerAndroid objects are converted to IPCs and then sent to the render
 // process.
 class CONTENT_EXPORT BrowserMediaPlayerManager
-    : public media::MediaPlayerManager,
-      public MediaSessionObserver {
+    : public media::MediaPlayerManager {
  public:
   // Permits embedders to provide an extended version of the class.
   typedef BrowserMediaPlayerManager* (*Factory)(RenderFrameHost*);
@@ -111,10 +109,6 @@ class CONTENT_EXPORT BrowserMediaPlayerManager
   void OnFrameInfoUpdated();
 #endif  // defined(VIDEO_HOLE)
 
-  // MediaSessionObserver overrides.
-  void OnSuspend(int player_id) override;
-  void OnResume(int player_id) override;
-
   // Message handlers.
   virtual void OnEnterFullscreen(int player_id);
   virtual void OnInitialize(