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

Source/modules/mediastream/RTCDataChannelEvent.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 16 matching lines @@
 
 #include "modules/EventModules.h"
 #include "modules/mediastream/RTCDataChannel.h"
 #include "wtf/text/AtomicString.h"
 
 namespace blink {
 
 class RTCDataChannelEvent final : public Event {
     DEFINE_WRAPPERTYPEINFO();
 public:
-    virtual ~RTCDataChannelEvent();
+    ~RTCDataChannelEvent() override;
 
     static PassRefPtrWillBeRawPtr<RTCDataChannelEvent> create();
     static PassRefPtrWillBeRawPtr<RTCDataChannelEvent> create(const AtomicString& type, bool canBubble, bool cancelable, RTCDataChannel*);
 
     RTCDataChannel* channel() const;
 
-    virtual const AtomicString& interfaceName() const override;
+    const AtomicString& interfaceName() const override;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     RTCDataChannelEvent();
     RTCDataChannelEvent(const AtomicString& type, bool canBubble, bool cancelable, RTCDataChannel*);
 
     PersistentWillBeMember<RTCDataChannel> m_channel;
 };
 
 } // namespace blink
 
 #endif // RTCDataChannelEvent_h