Fix virtual/override/final usage in Source/core/html/.

Source/core/html/MediaKeyEvent.h

 /*
  * Copyright (C) 2012 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 19 matching lines @@
 #include "core/dom/DOMTypedArray.h"
 #include "core/events/Event.h"
 #include "core/html/MediaKeyError.h"
 #include "core/html/MediaKeyEventInit.h"
 
 namespace blink {
 
 class CORE_EXPORT MediaKeyEvent final : public Event {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    virtual ~MediaKeyEvent();
+    ~MediaKeyEvent() override;
 
     static PassRefPtrWillBeRawPtr<MediaKeyEvent> create()
     {
         return adoptRefWillBeNoop(new MediaKeyEvent);
     }
 
     static PassRefPtrWillBeRawPtr<MediaKeyEvent> create(const AtomicString& type, const MediaKeyEventInit& initializer)
     {
         return adoptRefWillBeNoop(new MediaKeyEvent(type, initializer));
     }
 
-    virtual const AtomicString& interfaceName() const override;
+    const AtomicString& interfaceName() const override;
 
     String keySystem() const { return m_keySystem; }
     String sessionId() const { return m_sessionId; }
     DOMUint8Array* initData() const { return m_initData.get(); }
     DOMUint8Array* message() const { return m_message.get(); }
     String defaultURL() const { return m_defaultURL; }
     MediaKeyError* errorCode() const { return m_errorCode.get(); }
     unsigned short systemCode() const { return m_systemCode; }
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     MediaKeyEvent();
     MediaKeyEvent(const AtomicString& type, const MediaKeyEventInit& initializer);
 
     String m_keySystem;
     String m_sessionId;
     RefPtr<DOMUint8Array> m_initData;
     RefPtr<DOMUint8Array> m_message;
     String m_defaultURL;
     RefPtrWillBeMember<MediaKeyError> m_errorCode;
     unsigned short m_systemCode;
 };
 
 } // namespace blink
 
 #endif // MediaKeyEvent_h