Update platform classes to use OVERRIDE / FINAL when needed

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 64 matching lines @@
     ExtraData* extraData() const { return m_extraData.get(); }
     void setExtraData(PassRefPtr<ExtraData> extraData) { m_extraData = extraData; }
 
 private:
     MediaStreamComponent(const String& id, MediaStreamDescriptor*, PassRefPtr<MediaStreamSource>);
 
 #if ENABLE(WEB_AUDIO)
     // AudioSourceProviderImpl wraps a WebAudioSourceProvider::provideInput()
     // calls into chromium to get a rendered audio stream.
 
-    class AudioSourceProviderImpl : public AudioSourceProvider {
+    class AudioSourceProviderImpl FINAL: public AudioSourceProvider {
     public:
         AudioSourceProviderImpl()
             : m_webAudioSourceProvider(0)
         {
         }
 
         virtual ~AudioSourceProviderImpl() { }
 
         // Wraps the given blink::WebAudioSourceProvider to WebCore::AudioSourceProvider.
         void wrap(blink::WebAudioSourceProvider*);
 
         // WebCore::AudioSourceProvider
-        virtual void provideInput(WebCore::AudioBus*, size_t framesToProcess);
+        virtual void provideInput(WebCore::AudioBus*, size_t framesToProcess) OVERRIDE;
 
     private:
         blink::WebAudioSourceProvider* m_webAudioSourceProvider;
         Mutex m_provideInputLock;
     };
 
     AudioSourceProviderImpl m_sourceProvider;
 #endif // ENABLE(WEB_AUDIO)
 
     MediaStreamDescriptor* m_stream;
     RefPtr<MediaStreamSource> m_source;
     String m_id;
     bool m_enabled;
     RefPtr<ExtraData> m_extraData;
 };
 
 typedef Vector<RefPtr<MediaStreamComponent> > MediaStreamComponentVector;
 
 } // namespace WebCore
 
 #endif // MediaStreamComponent_h