Implement MediaSession on top of the WebMediaPlayerDelegate.

content/renderer/media/renderer_webmediaplayer_delegate.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 CONTENT_RENDERER_MEDIA_RENDERER_WEBMEDIAPLAYER_DELEGATE_H_
 #define CONTENT_RENDERER_MEDIA_RENDERER_WEBMEDIAPLAYER_DELEGATE_H_
 
+#include <set>
+
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "content/public/renderer/render_frame_observer.h"
 #include "media/blink/webmediaplayer_delegate.h"
 
 namespace blink {
 class WebMediaPlayer;
 }
 
@@ skipping 15 matching lines @@
   // WebMediaPlayerDelegate implementation.
   void DidPlay(blink::WebMediaPlayer* player) override;
   void DidPause(blink::WebMediaPlayer* player) override;
   void PlayerGone(blink::WebMediaPlayer* player) override;
   void AddObserver(Observer* observer) override;
   void RemoveObserver(Observer* observer) override;
 
   // content::RenderFrameObserver overrides.
   void WasHidden() override;
   void WasShown() override;
+  bool OnMessageReceived(const IPC::Message& msg) override;
 
  private:
+  void OnMediaDelegatePause(int64_t player_cookie);
+  void OnMediaDelegatePlay(int64_t player_cookie);
+
   bool has_played_media_ = false;
   base::ObserverList<Observer> observer_list_;
+  std::set<blink::WebMediaPlayer*> players_;
 
   DISALLOW_COPY_AND_ASSIGN(RendererWebMediaPlayerDelegate);
 };
 
 }  // namespace media
 
 #endif  // CONTENT_RENDERER_MEDIA_RENDERER_WEBMEDIAPLAYER_DELEGATE_H_