blink: Cleanup core class forward declarations

third_party/WebKit/Source/core/page/PageVisibilityObserver.h

 
 /*
  * Copyright (C) 2013 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 15 matching lines @@
 
 #ifndef PageVisibilityObserver_h
 #define PageVisibilityObserver_h
 
 #include "core/CoreExport.h"
 #include "core/page/Page.h"
 #include "platform/LifecycleObserver.h"
 
 namespace blink {
 
-class LocalFrame;
 
 class CORE_EXPORT PageVisibilityObserver
     : public LifecycleObserver<Page, PageVisibilityObserver> {
  public:
   virtual void pageVisibilityChanged() {}
 
   Page* page() const { return lifecycleContext(); }
 
  protected:
   explicit PageVisibilityObserver(Page* page) : LifecycleObserver(page) {}
 };
 
 }  // namespace blink
 
 #endif  // PageVisibilityObserver_h