Fix "unused variable" warnings.

content/renderer/media/webrtc/media_stream_remote_video_source.cc

 // 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.
 
 #include "content/renderer/media/webrtc/media_stream_remote_video_source.h"
 
 #include <stdint.h>
 #include <utility>
 
 #include "base/bind.h"
 #include "base/callback_helpers.h"
 #include "base/location.h"
-#include "base/threading/thread_checker.h"
 #include "base/trace_event/trace_event.h"
 #include "content/renderer/media/webrtc/track_observer.h"
 #include "media/base/bind_to_current_loop.h"
 #include "media/base/timestamp_constants.h"
 #include "media/base/video_frame.h"
 #include "media/base/video_util.h"
 #include "third_party/webrtc/media/base/videoframe.h"
 #include "third_party/webrtc/media/base/videosinkinterface.h"
 
 namespace content {
@@ skipping 14 matching lines @@
 
   // Implements rtc::VideoSinkInterface used for receiving video frames
   // from the PeerConnection video track. May be called on a libjingle internal
   // thread.
   void OnFrame(const cricket::VideoFrame& frame) override;
 
   void DoRenderFrameOnIOThread(
       const scoped_refptr<media::VideoFrame>& video_frame);
 
  private:
-  // Bound to the render thread.
-  base::ThreadChecker thread_checker_;
-
   scoped_refptr<base::SingleThreadTaskRunner> io_task_runner_;
 
   // |frame_callback_| is accessed on the IO thread.
   VideoCaptureDeliverFrameCB frame_callback_;
 
   // Timestamp of the first received frame.
   base::TimeDelta start_timestamp_;
   // WebRTC Chromium timestamp diff
   const base::TimeDelta time_diff_;
 };
@@ skipping 155 matching lines @@
     case webrtc::MediaStreamTrackInterface::kEnded:
       SetReadyState(blink::WebMediaStreamSource::ReadyStateEnded);
       break;
     default:
       NOTREACHED();
       break;
   }
 }
 
 }  // namespace content