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

Source/platform/LifecycleObserver.h

 /*
  * Copyright (C) 2008 Apple 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 16 matching lines @@
 #ifndef LifecycleObserver_h
 #define LifecycleObserver_h
 
 #include "platform/heap/Handle.h"
 #include "wtf/Assertions.h"
 
 namespace blink {
 
 template<typename T>
 class LifecycleObserver : public WillBeGarbageCollectedMixin {
-    // FIXME: Oilpan: Remove the pre-finalizer by moving LifecycleNotifier
-    // to Oilpan's heap and making LifecycleNotifier::m_observers
-    // a hash set of weak members.
-    WILL_BE_USING_PRE_FINALIZER(LifecycleObserver, dispose);
 public:
     typedef T Context;
 
     enum Type {
         ActiveDOMObjectType,
         DocumentLifecycleObserverType,
         GenericType,
         PageLifecycleObserverType,
         DOMWindowLifecycleObserverType
     };
 
     explicit LifecycleObserver(Context* context, Type type = GenericType)
         : m_lifecycleContext(nullptr)
         , m_observerType(type)
     {
-#if ENABLE(OILPAN)
-        ThreadState::current()->registerPreFinalizer(*this);
-#endif
         setContext(context);
     }
     virtual ~LifecycleObserver()
     {
 #if !ENABLE(OILPAN)
-        dispose();
+        setContext(nullptr);
 #endif
     }
 
     virtual void trace(Visitor* visitor)
     {
         visitor->trace(m_lifecycleContext);
     }
     virtual void contextDestroyed() { }
-    void dispose()
-    {
-        setContext(nullptr);
-    }
 
     Context* lifecycleContext() const { return m_lifecycleContext; }
     void clearLifecycleContext() { m_lifecycleContext = nullptr; }
     Type observerType() const { return m_observerType; }
 
 protected:
     void setContext(Context*);
 
     RawPtrWillBeWeakMember<Context> m_lifecycleContext;
     Type m_observerType;
@@ skipping 14 matching lines @@
 
     m_lifecycleContext = context;
 
     if (m_lifecycleContext)
         observeContext(m_lifecycleContext.get(), this);
 }
 
 } // namespace blink
 
 #endif // LifecycleObserver_h