Update {virtual,override} to follow C++11 style in content.

content/renderer/media/mock_media_stream_video_sink.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_MOCK_MEDIA_STREAM_VIDEO_SINK_H_
 #define CONTENT_RENDERER_MEDIA_MOCK_MEDIA_STREAM_VIDEO_SINK_H_
 
 #include "content/public/renderer/media_stream_video_sink.h"
 
 #include "base/memory/weak_ptr.h"
 #include "content/common/media/video_capture.h"
 #include "media/base/video_frame.h"
 #include "testing/gmock/include/gmock/gmock.h"
 
 namespace content {
 
 class MockMediaStreamVideoSink : public MediaStreamVideoSink {
  public:
   MockMediaStreamVideoSink();
-  virtual ~MockMediaStreamVideoSink();
+  ~MockMediaStreamVideoSink() override;
 
-  virtual void OnReadyStateChanged(
+  void OnReadyStateChanged(
       blink::WebMediaStreamSource::ReadyState state) override;
-  virtual void OnEnabledChanged(bool enabled) override;
+  void OnEnabledChanged(bool enabled) override;
 
   // Triggered when OnVideoFrame(const scoped_refptr<media::VideoFrame>& frame)
   // is called.
   MOCK_METHOD0(OnVideoFrame, void());
 
   VideoCaptureDeliverFrameCB GetDeliverFrameCB();
 
   int number_of_frames() const { return number_of_frames_; }
   media::VideoFrame::Format format() const { return format_; }
   gfx::Size frame_size() const { return frame_size_; }
@@ skipping 11 matching lines @@
   media::VideoFrame::Format format_;
   blink::WebMediaStreamSource::ReadyState state_;
   gfx::Size frame_size_;
   scoped_refptr<media::VideoFrame> last_frame_;
   base::WeakPtrFactory<MockMediaStreamVideoSink> weak_factory_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_MOCK_MEDIA_STREAM_VIDEO_SINK_H_