Enable -Winconsistent-missing-override flag.

webrtc/api/dtmfsender.h

 /*
  *  Copyright 2012 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 65 matching lines @@
  protected:
   DtmfSender(AudioTrackInterface* track,
              rtc::Thread* signaling_thread,
              DtmfProviderInterface* provider);
   virtual ~DtmfSender();
 
  private:
   DtmfSender();
 
   // Implements MessageHandler.
-  virtual void OnMessage(rtc::Message* msg);
+  void OnMessage(rtc::Message* msg) override;
 
   // The DTMF sending task.
   void DoInsertDtmf();
 
   void OnProviderDestroyed();
 
   void StopSending();
 
   rtc::scoped_refptr<AudioTrackInterface> track_;
   DtmfSenderObserverInterface* observer_;
@@ skipping 17 matching lines @@
   PROXY_CONSTMETHOD0(int, duration)
   PROXY_CONSTMETHOD0(int, inter_tone_gap)
 END_SIGNALING_PROXY()
 
 // Get DTMF code from the DTMF event character.
 bool GetDtmfCode(char tone, int* code);
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_API_DTMFSENDER_H_