Revert r189385 "Remove LifecycleContext" and r189391, r189530, r189456 that block it

Source/platform/LifecycleNotifier.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 22 matching lines @@
 #include "wtf/TemporaryChange.h"
 
 namespace blink {
 
 template<typename T>
 class LifecycleNotifier {
 public:
     typedef LifecycleObserver<T> Observer;
     typedef T Context;
 
+    static PassOwnPtr<LifecycleNotifier> create(Context* context)
+    {
+        return adoptPtr(new LifecycleNotifier(context));
+    }
+
     virtual ~LifecycleNotifier();
-    virtual bool isContextThread() const { return true; }
 
     // notifyContextDestroyed() should be explicitly dispatched from an
     // observed context to notify observers contextDestroyed().
     // At the point of contextDestroyed() is called, m_context is still
     // valid and thus it is safe to use m_context during the notification.
     virtual void notifyContextDestroyed();
 
     // FIXME: this won't need to be virtual anymore.
     virtual void addObserver(Observer*);
     virtual void removeObserver(Observer*);
 
-    virtual void trace(Visitor*) { }
+    bool isIteratingOverObservers() const { return m_iterating != IteratingNone; }
 
 protected:
     explicit LifecycleNotifier(Context* context)
         : m_iterating(IteratingNone)
         , m_context(context)
         , m_didCallContextDestroyed(false)
     {
     }
 
     Context* context() const { return m_context; }
@@ skipping 17 matching lines @@
     bool m_didCallContextDestroyed;
 };
 
 template<typename T>
 inline LifecycleNotifier<T>::~LifecycleNotifier()
 {
     // FIXME: Enable the following ASSERT. Also see a FIXME in Document::detach().
     // ASSERT(!m_observers.size() || m_didCallContextDestroyed);
 
 #if !ENABLE(OILPAN)
-    TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
+    TemporaryChange<IterationType> scope(this->m_iterating, IteratingOverAll);
     for (Observer* observer : m_observers) {
         ASSERT(observer->lifecycleContext() == m_context);
         observer->clearLifecycleContext();
     }
 #endif
 }
 
 template<typename T>
 inline void LifecycleNotifier<T>::notifyContextDestroyed()
 {
     // Don't notify contextDestroyed() twice.
     if (m_didCallContextDestroyed)
         return;
 
-    TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
+    TemporaryChange<IterationType> scope(this->m_iterating, IteratingOverAll);
     Vector<Observer*> snapshotOfObservers;
     copyToVector(m_observers, snapshotOfObservers);
     for (Observer* observer : snapshotOfObservers) {
         // FIXME: Oilpan: At the moment, it's possible that the Observer is
         // destructed during the iteration. Once we enable Oilpan by default
         // for Observers, we can remove the hack by making m_observers
         // a HeapHashSet<WeakMember<Observers>>. (i.e., we can just iterate
         // m_observers without taking a snapshot).
         if (m_observers.contains(observer)) {
             ASSERT(observer->lifecycleContext() == m_context);
@@ skipping 12 matching lines @@
 
 template<typename T>
 inline void LifecycleNotifier<T>::removeObserver(typename LifecycleNotifier<T>::Observer* observer)
 {
     m_observers.remove(observer);
 }
 
 } // namespace blink
 
 #endif // LifecycleNotifier_h