MediaStreamVideo*/VideoTrackAdapter and RTCVideoRenderer (small) cleanup

content/renderer/media/media_stream_video_source.h

 // Copyright 2014 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_MEDIA_STREAM_VIDEO_SOURCE_H_
 #define CONTENT_RENDERER_MEDIA_MEDIA_STREAM_VIDEO_SOURCE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 152 matching lines @@
     MediaStreamVideoTrack* track;
     VideoCaptureDeliverFrameCB frame_callback;
     blink::WebMediaConstraints constraints;
     ConstraintsCallback callback;
   };
   std::vector<RequestedConstraints> requested_constraints_;
 
   media::VideoCaptureFormats supported_formats_;
 
   // |track_adapter_| delivers video frames to the tracks on the IO-thread.
-  scoped_refptr<VideoTrackAdapter> track_adapter_;
+  const scoped_refptr<VideoTrackAdapter> track_adapter_;
 
   // Tracks that currently are connected to this source.
   std::vector<MediaStreamVideoTrack*> tracks_;
 
   // NOTE: Weak pointers must be invalidated before all other member variables.
   base::WeakPtrFactory<MediaStreamVideoSource> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MediaStreamVideoSource);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_MEDIA_STREAM_VIDEO_SOURCE_H_