Oilpan: Move LifecycleNotifier's hierarchy to Oilpan's heap

Source/core/dom/ContextLifecycleNotifier.h

 /*
  * Copyright (C) 2008 Apple Inc. All Rights Reserved.
  * 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 21 matching lines @@
 #include "wtf/HashSet.h"
 #include "wtf/PassOwnPtr.h"
 
 namespace blink {
 
 class ActiveDOMObject;
 class ExecutionContext;
 
 class ContextLifecycleNotifier : public LifecycleNotifier<ExecutionContext> {
 public:
-    typedef HashSet<ActiveDOMObject*> ActiveDOMObjectSet;
+    typedef WillBeHeapHashSet<RawPtrWillBeWeakMember<ActiveDOMObject>> ActiveDOMObjectSet;
 
     const ActiveDOMObjectSet& activeDOMObjects() const { return m_activeDOMObjects; }
 
     virtual void addObserver(Observer*) override;
     virtual void removeObserver(Observer*) override;
 
     void notifyResumingActiveDOMObjects();
     void notifySuspendingActiveDOMObjects();
     void notifyStoppingActiveDOMObjects();
 
     bool contains(ActiveDOMObject* object) const { return m_activeDOMObjects.contains(object); }
     bool hasPendingActivity() const;
 
+    virtual void trace(Visitor*) override;
+
 protected:
     explicit ContextLifecycleNotifier(ExecutionContext*);
 
 private:
     ActiveDOMObjectSet m_activeDOMObjects;
 };
 
 } // namespace blink
 
 #endif // ContextLifecycleNotifier_h