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

Source/platform/mediastream/MediaStreamComponent.h

 /*
  * Copyright (C) 2011 Ericsson AB. All rights reserved.
  * Copyright (C) 2013 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.
@@ skipping 66 matching lines @@
     // AudioSourceProviderImpl wraps a WebAudioSourceProvider::provideInput()
     // calls into chromium to get a rendered audio stream.
 
     class PLATFORM_EXPORT AudioSourceProviderImpl final: public AudioSourceProvider {
     public:
         AudioSourceProviderImpl()
             : m_webAudioSourceProvider(0)
         {
         }
 
-        virtual ~AudioSourceProviderImpl() { }
+        ~AudioSourceProviderImpl() override {}
 
         // Wraps the given blink::WebAudioSourceProvider to blink::AudioSourceProvider.
         void wrap(WebAudioSourceProvider*);
 
         // blink::AudioSourceProvider
-        virtual void provideInput(AudioBus*, size_t framesToProcess) override;
+        void provideInput(AudioBus*, size_t framesToProcess) override;
 
     private:
         WebAudioSourceProvider* m_webAudioSourceProvider;
         Mutex m_provideInputLock;
     };
 
     AudioSourceProviderImpl m_sourceProvider;
 #endif // ENABLE(WEB_AUDIO)
 
     RefPtr<MediaStreamSource> m_source;
     String m_id;
     bool m_enabled;
     bool m_muted;
     OwnPtr<ExtraData> m_extraData;
 };
 
 typedef Vector<RefPtr<MediaStreamComponent>> MediaStreamComponentVector;
 
 } // namespace blink
 
 #endif // MediaStreamComponent_h