Explictly clear LifecycleObserver's context

third_party/WebKit/Source/platform/LifecycleNotifier.h

Index: third_party/WebKit/Source/platform/LifecycleNotifier.h
diff --git a/third_party/WebKit/Source/platform/LifecycleNotifier.h b/third_party/WebKit/Source/platform/LifecycleNotifier.h
index d3a30896905d91f97a88a483344259de873ed52f..b891c09db4601458ce5db580240c46d48bf03822 100644
--- a/third_party/WebKit/Source/platform/LifecycleNotifier.h
+++ b/third_party/WebKit/Source/platform/LifecycleNotifier.h
@@ -60,7 +60,6 @@ public:
 protected:
     LifecycleNotifier()
         : m_iterating(IteratingNone)
-        , m_didCallContextDestroyed(false)
     {
     }
 
@@ -79,16 +78,13 @@ protected:
 #if ENABLE(ASSERT)
     T* context() { return static_cast<T*>(this); }
 #endif
-
-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);
+    // ASSERT(!m_observers.size());
 
 #if !ENABLE(OILPAN)
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
@@ -102,7 +98,7 @@ template<typename T, typename Observer>
 inline void LifecycleNotifier<T, Observer>::notifyContextDestroyed()
 {
     // Don't notify contextDestroyed() twice.
-    if (m_didCallContextDestroyed)
+    if (m_observers.isEmpty())
         return;
 
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
@@ -119,10 +115,10 @@ inline void LifecycleNotifier<T, Observer>::notifyContextDestroyed()
         if (m_observers.contains(observer)) {
             ASSERT(observer->lifecycleContext() == context());
             observer->contextDestroyed();
+            observer->clearLifecycleContext();
         }
     }
-
-    m_didCallContextDestroyed = true;
+    m_observers.clear();
 }
 
 template<typename T, typename Observer>