Robustify state-transitions in HTMLMediaElement::startDeferredLoad

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple 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 1098 matching lines @@
 
     startPlayerLoad();
 }
 
 void HTMLMediaElement::startDeferredLoad()
 {
     if (m_deferredLoadState == WaitingForTrigger) {
         executeDeferredLoad();
         return;
     }
+    if (m_deferredLoadState == ExecuteOnStopDelayingLoadEventTask)
+        return;
     ASSERT(m_deferredLoadState == WaitingForStopDelayingLoadEventTask);
     m_deferredLoadState = ExecuteOnStopDelayingLoadEventTask;
 }
 
 void HTMLMediaElement::deferredLoadTimerFired(Timer<HTMLMediaElement>*)
 {
     setShouldDelayLoadEvent(false);
 
     if (m_deferredLoadState == ExecuteOnStopDelayingLoadEventTask) {
         executeDeferredLoad();
@@ skipping 2543 matching lines @@
     visitor->trace(m_client);
 }
 
 DEFINE_TRACE(HTMLMediaElement::AudioSourceProviderImpl)
 {
     visitor->trace(m_client);
 }
 #endif
 
 }