Revert of Revert of Oilpan: Prepare to make ExecutionContext GarbageCollectedMixin.

Source/modules/filesystem/FileSystemCallbacks.h

 /*
  * Copyright (C) 2010 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
@@ skipping 56 matching lines @@
     bool shouldScheduleCallback() const;
 
     template <typename CB, typename CBArg>
     void handleEventOrScheduleCallback(PassOwnPtr<CB>, PassRefPtrWillBeRawPtr<CBArg>);
 
     template <typename CB>
     void handleEventOrScheduleCallback(PassOwnPtr<CB>);
 
     OwnPtr<ErrorCallback> m_errorCallback;
     RefPtrWillBePersistent<DOMFileSystemBase> m_fileSystem;
-    RefPtr<ExecutionContext> m_executionContext;
+    RefPtrWillBePersistent<ExecutionContext> m_executionContext;
 };
 
 // Subclasses ----------------------------------------------------------------
 
 class EntryCallbacks FINAL : public FileSystemCallbacksBase {
 public:
     static PassOwnPtr<AsyncFileSystemCallbacks> create(PassOwnPtr<EntryCallback>, PassOwnPtr<ErrorCallback>, ExecutionContext*, PassRefPtrWillBeRawPtr<DOMFileSystemBase>, const String& expectedPath, bool isDirectory);
     virtual void didSucceed() OVERRIDE;
 
 private:
@@ skipping 65 matching lines @@
     virtual void didSucceed() OVERRIDE;
 
 private:
     VoidCallbacks(PassOwnPtr<VoidCallback>, PassOwnPtr<ErrorCallback>, ExecutionContext*, PassRefPtrWillBeRawPtr<DOMFileSystemBase>);
     OwnPtr<VoidCallback> m_successCallback;
 };
 
 } // namespace
 
 #endif // FileSystemCallbacks_h