Add a layer of indirection between Frame and Page

Source/core/frame/FrameDestructionObserver.h

 /*
  * Copyright (C) 2011 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 @@
 
 namespace WebCore {
 
 class Frame;
 
 class FrameDestructionObserver {
 public:
     explicit FrameDestructionObserver(Frame*);
 
     virtual void frameDestroyed();
-    virtual void willDetachPage();
+    virtual void willDetachFrameHost();
 
     Frame* frame() const { return m_frame; }
 
 protected:
     virtual ~FrameDestructionObserver();
     void observeFrame(Frame*);
 
     Frame* m_frame;
 };
 
 }
 
 #endif