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

Source/modules/mediastream/RTCSessionDescriptionRequestImpl.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
@@ skipping 30 matching lines @@
 
 class RTCErrorCallback;
 class RTCPeerConnection;
 class RTCSessionDescriptionCallback;
 class WebRTCSessionDescription;
 
 class RTCSessionDescriptionRequestImpl final : public RTCSessionDescriptionRequest, public ActiveDOMObject {
     WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(RTCSessionDescriptionRequestImpl);
 public:
     static RTCSessionDescriptionRequestImpl* create(ExecutionContext*, RTCPeerConnection*, RTCSessionDescriptionCallback*, RTCErrorCallback*);
-    virtual ~RTCSessionDescriptionRequestImpl();
+    ~RTCSessionDescriptionRequestImpl() override;
 
-    virtual void requestSucceeded(const WebRTCSessionDescription&) override;
-    virtual void requestFailed(const String& error) override;
+    void requestSucceeded(const WebRTCSessionDescription&) override;
+    void requestFailed(const String& error) override;
 
     // ActiveDOMObject
-    virtual void stop() override;
+    void stop() override;
 
     DECLARE_VIRTUAL_TRACE();
 
 private:
     RTCSessionDescriptionRequestImpl(ExecutionContext*, RTCPeerConnection*, RTCSessionDescriptionCallback*, RTCErrorCallback*);
 
     void clear();
 
     Member<RTCSessionDescriptionCallback> m_successCallback;
     Member<RTCErrorCallback> m_errorCallback;
     Member<RTCPeerConnection> m_requester;
 };
 
 } // namespace blink
 
 #endif // RTCSessionDescriptionRequestImpl_h