Simplify LifecycleNotifier and Observer.

third_party/WebKit/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 32 matching lines @@
 
     // notifyContextDestroyed() should be explicitly dispatched from an
     // observed context to notify observers that contextDestroyed().
     //
     // When contextDestroyed() is called, the observer's lifecycleContext()
     // is still valid and safe to use during the notification.
     virtual void notifyContextDestroyed();
 
     DEFINE_INLINE_VIRTUAL_TRACE()
     {
-#if ENABLE(OILPAN)
         visitor->trace(m_observers);
-#endif
     }
 
     bool isIteratingOverObservers() const { return m_iterating != IteratingNone; }
 
 protected:
     LifecycleNotifier()
         : m_iterating(IteratingNone)
         , m_didCallContextDestroyed(false)
     {
     }
@@ skipping 16 matching lines @@
 
 private:
     bool m_didCallContextDestroyed;
 };
 
 template<typename T, typename Observer>
 inline LifecycleNotifier<T, Observer>::~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);
-    for (Observer* observer : m_observers) {
-        observer->clearLifecycleContext();
-    }
-#endif
 }
 
 template<typename T, typename Observer>
 inline void LifecycleNotifier<T, Observer>::notifyContextDestroyed()
 {
     // Don't notify contextDestroyed() twice.
     if (m_didCallContextDestroyed)
         return;
 
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
     Vector<UntracedMember<Observer>> snapshotOfObservers;
     copyToVector(m_observers, snapshotOfObservers);
     for (Observer* observer : snapshotOfObservers) {
-        // FIXME: Oilpan: At the moment, it's possible that the Observer is

[sof, 2016/04/04 09:47:32]

Removed this FIXME as it doesn't hold (&something we've repeatedly discovered.)

-        // destructed during the iteration.
-        // Once we enable Oilpan by default for Observers *and*
-        // Observer::contextDestroyed() does not call removeObserver(),
-        // 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() == context());
-            observer->contextDestroyed();
-        }
+        if (!m_observers.contains(observer))
+            continue;
+
+        ASSERT(observer->lifecycleContext() == context());
+        observer->contextDestroyed();
     }
 
     m_didCallContextDestroyed = true;
 }
 
 template<typename T, typename Observer>
 inline void LifecycleNotifier<T, Observer>::addObserver(Observer* observer)
 {
     RELEASE_ASSERT(m_iterating != IteratingOverAll);
     m_observers.add(observer);
 }
 
 template<typename T, typename Observer>
 inline void LifecycleNotifier<T, Observer>::removeObserver(Observer* observer)
 {
     m_observers.remove(observer);
 }
 
 } // namespace blink
 
 #endif // LifecycleNotifier_h