Fix VideoCapturer::OnMessage override

webrtc/media/base/videocapturer.h

 /*
  *  Copyright (c) 2010 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 271 matching lines @@
   void OnFrameCaptured(VideoCapturer* video_capturer,
                        const CapturedFrame* captured_frame);
 
   // Callback attached to SignalVideoFrame.
   // TODO(perkj): Remove once SignalVideoFrame is removed.
   void OnFrame(VideoCapturer* capturer, const VideoFrame* frame);
 
   void SetCaptureState(CaptureState state);
 
   // Marshals SignalStateChange onto thread_.
-  void OnMessage(rtc::Message* message);
+  void OnMessage(rtc::Message* message) override;
 
   // subclasses override this virtual method to provide a vector of fourccs, in
   // order of preference, that are expected by the media engine.
   virtual bool GetPreferredFourccs(std::vector<uint32_t>* fourccs) = 0;
 
   // mutators to set private attributes
   void SetId(const std::string& id) {
     id_ = id;
   }
 
@@ skipping 70 matching lines @@
 
   // Whether capturer should apply rotation to the frame before signaling it.
   bool apply_rotation_;
 
   RTC_DISALLOW_COPY_AND_ASSIGN(VideoCapturer);
 };
 
 }  // namespace cricket
 
 #endif  // WEBRTC_MEDIA_BASE_VIDEOCAPTURER_H_