Fix virtual/override/final usage in Source/modules/.

Source/modules/webaudio/GainNode.h

 /*
  * Copyright (C) 2010, Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1.  Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 24 matching lines @@
 class AudioContext;
 
 // GainNode is an AudioNode with one input and one output which applies a gain (volume) change to the audio signal.
 // De-zippering (smoothing) is applied when the gain value is changed dynamically.
 
 class GainHandler final : public AudioHandler {
 public:
     static PassRefPtr<GainHandler> create(AudioNode&, float sampleRate, AudioParamHandler& gain);
 
     // AudioHandler
-    virtual void process(size_t framesToProcess) override;
+    void process(size_t framesToProcess) override;
 
     // Called in the main thread when the number of channels for the input may have changed.
-    virtual void checkNumberOfChannelsForInput(AudioNodeInput*) override;
+    void checkNumberOfChannelsForInput(AudioNodeInput*) override;
 
 private:
     GainHandler(AudioNode&, float sampleRate, AudioParamHandler& gain);
 
     float m_lastGain; // for de-zippering
     RefPtr<AudioParamHandler> m_gain;
 
     AudioFloatArray m_sampleAccurateGainValues;
 };
 
 class GainNode final : public AudioNode {
     DEFINE_WRAPPERTYPEINFO();
 public:
     static GainNode* create(AudioContext&, float sampleRate);
     DECLARE_VIRTUAL_TRACE();
 
     AudioParam* gain() const;
 
 private:
     GainNode(AudioContext&, float sampleRate);
 
     Member<AudioParam> m_gain;
 };
 
 } // namespace blink
 
 #endif // GainNode_h