Standardize usage of virtual/override/final in content/renderer/

content/renderer/media/rtc_dtmf_sender_handler.h

 // Copyright (c) 2013 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_RTC_DTMF_SENDER_HANDLER_H_
 #define CONTENT_RENDERER_MEDIA_RTC_DTMF_SENDER_HANDLER_H_
 
 #include <string>
 
 #include "base/memory/ref_counted.h"
@@ skipping 21 matching lines @@
 
   // blink::WebRTCDTMFSenderHandler implementation.
   virtual void setClient(
       blink::WebRTCDTMFSenderHandlerClient* client) override;
   virtual blink::WebString currentToneBuffer() override;
   virtual bool canInsertDTMF() override;
   virtual bool insertDTMF(const blink::WebString& tones, long duration,
                           long interToneGap) override;
 
   // webrtc::DtmfSenderObserverInterface implementation.
-  virtual void OnToneChange(const std::string& tone) override;
+  void OnToneChange(const std::string& tone) override;
 
  private:
   scoped_refptr<webrtc::DtmfSenderInterface> dtmf_sender_;
   blink::WebRTCDTMFSenderHandlerClient* webkit_client_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_RENDERER_MEDIA_RTC_DTMF_SENDER_HANDLER_H_