Decouple MediaSession messages from WebContents (full patch)

content/browser/media/session/media_session_controller.h

Index: content/browser/media/session/media_session_controller.h
diff --git a/content/browser/media/session/media_session_controller.h b/content/browser/media/session/media_session_controller.h
index 4017f533a2d52c5ccd278ab7ac6c3f3e07b2aced..f709828bd2b41f52e46511882cad666d71411951 100644
--- a/content/browser/media/session/media_session_controller.h
+++ b/content/browser/media/session/media_session_controller.h
@@ -17,7 +17,7 @@ enum class MediaContentType;
 
 namespace content {
 
-class MediaSession;
+class MediaSessionImpl;
 class MediaWebContentsObserver;
 
 // Helper class for controlling a single player's MediaSession instance.  Sends
@@ -61,7 +61,7 @@ class CONTENT_EXPORT MediaSessionController
   MediaWebContentsObserver* const media_web_contents_observer_;
 
   // Non-owned pointer; lifetime is the same as |media_web_contents_observer_|.
-  MediaSession* const media_session_;
+  MediaSessionImpl* const media_session_;
 
   int player_id_ = 0;
   bool has_session_ = false;