LifecycleObserver::contextDestroyed should be explicitly dispatched promptly when a context is dest…

Source/platform/LifecycleContext.h

 
 /*
  * 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 26 matching lines @@
 namespace blink {
 
 class Visitor;
 
 template <typename T>
 class LifecycleContext {
 public:
     typedef LifecycleNotifier<T> Notifier;
     typedef LifecycleObserver<T> Observer;
 
-    LifecycleContext() { }
-    virtual ~LifecycleContext() { }
+    LifecycleContext()
+#if ENABLE(ASSERT)
+        : m_contextDestroyed(false)
+#endif
+    {
+    }
+    virtual ~LifecycleContext()
+    {
+        ASSERT(m_contextDestroyed);
+    }
 
     virtual bool isContextThread() const { return true; }
 
     // Called from the constructor of observers.
     void wasObservedBy(Observer*);
 
     // Called from the destructor of observers.
     void wasUnobservedBy(Observer*);
 
     virtual void trace(Visitor*) { }
 
 protected:
     Notifier& lifecycleNotifier();
+    void contextDestroyed()
+    {
+#if ENABLE(ASSERT)
+        ASSERT(!m_contextDestroyed);
+        m_contextDestroyed = true;
+#endif
+        if (m_lifecycleNotifier)
+            m_lifecycleNotifier->contextDestroyed();
+    }
 
 private:
     PassOwnPtr<Notifier> createLifecycleNotifier();
 
     OwnPtr<Notifier> m_lifecycleNotifier;
+    bool m_contextDestroyed;
 };
 
 template<typename T>
 inline void LifecycleContext<T>::wasObservedBy(typename LifecycleContext<T>::Observer* observer)
 {
     ASSERT(isContextThread());
     lifecycleNotifier().addObserver(observer);
 }
 
 template<typename T>
@@ skipping 13 matching lines @@
 
 template<typename T>
 inline PassOwnPtr<typename LifecycleContext<T>::Notifier> LifecycleContext<T>::createLifecycleNotifier()
 {
     return LifecycleContext<T>::Notifier::create(static_cast<T*>(this));
 }
 
 } // namespace blink
 
 #endif // LifecycleContext_h