Virtualize EventDispatchMediator creation and cleanup calling.

Source/core/events/GestureEvent.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:
  *  * Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  *  * Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 28 matching lines @@
 
     static PassRefPtrWillBeRawPtr<GestureEvent> create(PassRefPtrWillBeRawPtr<AbstractView>, const PlatformGestureEvent&);
 
     bool isGestureEvent() const override;
 
     const AtomicString& interfaceName() const override;
 
     float deltaX() const { return m_deltaX; }
     float deltaY() const { return m_deltaY; }
 
+    PassRefPtrWillBeRawPtr<EventDispatchMediator> createMediator() override;
+
     DECLARE_VIRTUAL_TRACE();
 
 private:
     GestureEvent();
     GestureEvent(const AtomicString& type, PassRefPtrWillBeRawPtr<AbstractView>, int screenX, int screenY, int clientX, int clientY, bool ctrlKey, bool altKey, bool shiftKey, bool metaKey, float deltaX, float deltaY, double uiTimeStamp);
 
     float m_deltaX;
     float m_deltaY;
 };
 
@@ skipping 10 matching lines @@
     GestureEvent& event() const;
 
     bool dispatchEvent(EventDispatcher&) const override;
 };
 
 DEFINE_EVENT_TYPE_CASTS(GestureEvent);
 
 } // namespace blink
 
 #endif // GestureEvent_h