Disable background video track behind a feature flag

third_party/WebKit/public/platform/WebMediaPlayerClient.h

 /*
  * Copyright (C) 2009 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 83 matching lines @@
   virtual void disconnectedFromRemoteDevice() = 0;
   virtual void cancelledRemotePlaybackRequest() = 0;
   virtual void remotePlaybackStarted() = 0;
 
   // Returns whether the media element is in an autoplay muted state.
   virtual bool isAutoplayingMuted() = 0;
 
   // Warning: This method will destruct the caller.
   virtual void requestReload(const WebURL& newUrl) = 0;
 
+  // Returns if there's a selected video track.
+  virtual bool hasSelectedVideoTrack() = 0;
+
+  // Returns the selected video track id (or an empty id if there's none).
+  virtual WebMediaPlayer::TrackId getSelectedVideoTrackId() = 0;
+
  protected:
   ~WebMediaPlayerClient() {}
 };
 
 }  // namespace blink
 
 #endif