Implement MediaSession on top of the WebMediaPlayerDelegate.

media/blink/renderer_media_player_interface.h

Index: media/blink/renderer_media_player_interface.h
diff --git a/media/blink/renderer_media_player_interface.h b/media/blink/renderer_media_player_interface.h
index db50f8f37c5b8c0cef869d238c42f9d991a99ad4..dbda5596779811905f35c772b2ffbd017daf97d3 100644
--- a/media/blink/renderer_media_player_interface.h
+++ b/media/blink/renderer_media_player_interface.h
@@ -13,6 +13,7 @@
 
 #include <string>
 #include "base/time/time.h"
+#include "media/blink/webmediaplayer_delegate.h"
 #include "ui/gfx/geometry/rect_f.h"
 #include "url/gurl.h"
 
@@ -79,13 +80,15 @@ class RendererMediaPlayerInterface {
 class RendererMediaPlayerManagerInterface {
  public:
   // Initializes a MediaPlayerAndroid object in browser process.
-  virtual void Initialize(MediaPlayerHostMsg_Initialize_Type type,
-                          int player_id,
-                          const GURL& url,
-                          const GURL& first_party_for_cookies,
-                          int demuxer_client_id,
-                          const GURL& frame_url,
-                          bool allow_credentials) = 0;
+  virtual void Initialize(
+      MediaPlayerHostMsg_Initialize_Type type,
+      int player_id,
+      const GURL& url,
+      const GURL& first_party_for_cookies,
+      int demuxer_client_id,
+      const GURL& frame_url,
+      bool allow_credentials,
+      media::WebMediaPlayerDelegate::Observer* observer) = 0;
 
   // Starts the player.
   virtual void Start(int player_id) = 0;