Oilpan: support observer retirement during lifetime notifications.

Source/core/dom/DocumentLifecycleNotifier.cpp

 /*
  * 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 16 matching lines @@
 #include "config.h"
 #include "core/dom/DocumentLifecycleNotifier.h"
 
 #include "core/dom/DocumentLifecycleObserver.h"
 
 namespace blink {
 
 void DocumentLifecycleNotifier::notifyDocumentWasDetached()
 {
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
+#if !ENABLE(OILPAN)
+    // Notifications perform unknown amounts of heap allocations,
+    // which might trigger (conservative) GCs. This will flush out
+    // dead observers, causing the _non-heap_ set be updated. Snapshot
+    // the observers and explicitly check if they're still alive before
+    // notifying.
+    Vector<RawPtr<DocumentLifecycleObserver>> snapshotOfObservers;
+    copyToVector(m_observers, snapshotOfObservers);
+    for (DocumentLifecycleObserver* observer : snapshotOfObservers) {
+        if (m_observers.contains(observer))
+            observer->documentWasDetached();
+    }
+#else
     for (DocumentLifecycleObserver* observer : m_observers)
         observer->documentWasDetached();
+#endif
 }
 
 #if !ENABLE(OILPAN)
 void DocumentLifecycleNotifier::notifyDocumentWasDisposed()
 {
     TemporaryChange<IterationType> scope(m_iterating, IteratingOverAll);
-    for (DocumentLifecycleObserver* observer : m_observers)
-        observer->documentWasDisposed();
+    // Notifications perform unknown amounts of heap allocations,
+    // which might trigger (conservative) GCs. This will flush out
+    // dead observers, causing the _non-heap_ set be updated. Snapshot
+    // the observers and explicitly check if they're still alive before
+    // notifying.
+    Vector<RawPtr<DocumentLifecycleObserver>> snapshotOfObservers;
+    copyToVector(m_observers, snapshotOfObservers);
+    for (DocumentLifecycleObserver* observer : snapshotOfObservers) {
+        if (m_observers.contains(observer))
+            observer->documentWasDisposed();
+    }
 }
 #endif
 
 } // namespace blink