Clean up forward declarations in Source/core/page

Source/core/page/PointerLockController.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 17 matching lines @@
 #include "platform/heap/Handle.h"
 #include "wtf/RefPtr.h"
 #include "wtf/text/AtomicString.h"
 
 namespace blink {
 
 class Element;
 class Document;
 class Page;
 class PlatformMouseEvent;
-class VoidCallback;
 
 class PointerLockController FINAL : public NoBaseWillBeGarbageCollected<PointerLockController> {
     WTF_MAKE_NONCOPYABLE(PointerLockController);
     WTF_MAKE_FAST_ALLOCATED_WILL_BE_REMOVED;
 public:
     static PassOwnPtrWillBeRawPtr<PointerLockController> create(Page*);
 
     void requestPointerLock(Element* target);
     void requestPointerUnlock();
     void elementRemoved(Element*);
@@ skipping 16 matching lines @@
 
     RawPtrWillBeMember<Page> m_page;
     bool m_lockPending;
     RefPtrWillBeMember<Element> m_element;
     RefPtrWillBeMember<Document> m_documentOfRemovedElementWhileWaitingForUnlock;
 };
 
 } // namespace blink
 
 #endif // PointerLockController_h