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 428214d2aade61828f772870faad7f9a5035d408..506d1ec912b5b2803027d2477110d5b91aad6c3f 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*);
@@ -112,10 +110,6 @@ 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(
@@ -172,6 +166,8 @@ class CONTENT_EXPORT BrowserMediaPlayerManager
   // is stuck in an error.
   virtual void OnDecoderResourcesReleased(int player_id);
 
+  virtual bool IsPlayingRemotely(int player_id);

[mlamouri (slow - plz ping), 2016/01/19 16:59:11]

FWIW, zqzhang@ has a similar change.

+
   int RoutingID();
 
   // Helper function to send messages to RenderFrameObserver.
@@ -230,6 +226,10 @@ class CONTENT_EXPORT BrowserMediaPlayerManager
   // Object for retrieving resources media players.
   scoped_ptr<media::MediaResourceGetter> media_resource_getter_;
 
+  // Map of player IDs to delegate IDs for use with
+  // MediaWebContentsObserverAndroid.
+  std::map<int, int64_t> player_id_to_delegate_id_map_;
+
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<BrowserMediaPlayerManager> weak_ptr_factory_;