Make StorageArea cleanly observe its cached frame

Source/core/storage/StorageArea.h

 /*
  * Copyright (C) 2009 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
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  *
  * THIS SOFTWARE IS PROVIDED BY GOOGLE INC. ``AS IS'' AND ANY
  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL GOOGLE INC. OR
  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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 #ifndef StorageArea_h
 #define StorageArea_h
 
+#include "core/frame/FrameDestructionObserver.h"
 #include "platform/heap/Handle.h"
 #include "wtf/OwnPtr.h"
 #include "wtf/PassOwnPtr.h"
 #include "wtf/text/WTFString.h"
 
 namespace blink {
 
 class ExceptionState;
 class LocalFrame;
 class KURL;
 class Page;
 class SecurityOrigin;
 class Storage;
 class WebStorageArea;
 class WebStorageNamespace;
 
 enum StorageType {
     LocalStorage,
     SessionStorage
 };
 
-class StorageArea FINAL : public NoBaseWillBeGarbageCollectedFinalized<StorageArea> {
+class StorageArea FINAL : public NoBaseWillBeGarbageCollectedFinalized<StorageArea>, public FrameDestructionObserver {
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(StorageArea);
 public:
     static PassOwnPtrWillBeRawPtr<StorageArea> create(PassOwnPtr<WebStorageArea>, StorageType);
 
     virtual ~StorageArea();
 
     // The HTML5 DOM Storage API
     unsigned length(ExceptionState&, LocalFrame* sourceFrame);
     String key(unsigned index, ExceptionState&, LocalFrame* sourceFrame);
     String getItem(const String& key, ExceptionState&, LocalFrame* sourceFrame);
     void setItem(const String& key, const String& value, ExceptionState&, LocalFrame* sourceFrame);
@@ skipping 12 matching lines @@
 
     void trace(Visitor*);
 
 private:
     StorageArea(PassOwnPtr<WebStorageArea>, StorageType);
 
     static bool isEventSource(Storage*, WebStorageArea* sourceAreaInstance);
 
     OwnPtr<WebStorageArea> m_storageArea;
     StorageType m_storageType;
-    RawPtrWillBeMember<LocalFrame> m_canAccessStorageCachedFrame;
     bool m_canAccessStorageCachedResult;
 };
 
 } // namespace blink
 
 #endif // StorageArea_h