Standardize usage of virtual/override/final in media/

media/audio/simple_sources.h

 // Copyright (c) 2012 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 MEDIA_AUDIO_SIMPLE_SOURCES_H_
 #define MEDIA_AUDIO_SIMPLE_SOURCES_H_
 
 #include "base/synchronization/lock.h"
 #include "media/audio/audio_io.h"
 #include "media/base/seekable_buffer.h"
 
 namespace media {
 
 // An audio source that produces a pure sinusoidal tone.
 class MEDIA_EXPORT SineWaveAudioSource
     : public AudioOutputStream::AudioSourceCallback {
  public:
   // |channels| is the number of audio channels, |freq| is the frequency in
   // hertz and it has to be less than half of the sampling frequency
   // |sample_freq| or else you will get aliasing.
   SineWaveAudioSource(int channels, double freq, double sample_freq);
-  virtual ~SineWaveAudioSource() {}
+  ~SineWaveAudioSource() override {}
 
   // Return up to |cap| samples of data via OnMoreData().  Use Reset() to
   // allow more data to be served.
   void CapSamples(int cap);
   void Reset();
 
   // Implementation of AudioSourceCallback.
-  virtual int OnMoreData(AudioBus* audio_bus,
-                         uint32 total_bytes_delay) override;
-  virtual void OnError(AudioOutputStream* stream) override;
+  int OnMoreData(AudioBus* audio_bus, uint32 total_bytes_delay) override;
+  void OnError(AudioOutputStream* stream) override;
 
   // The number of OnMoreData() and OnError() calls respectively.
   int callbacks() { return callbacks_; }
   int errors() { return errors_; }
 
  protected:
   int channels_;
   double f_;
   int time_state_;
   int cap_;
   int callbacks_;
   int errors_;
   base::Lock time_lock_;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_SIMPLE_SOURCES_H_