Fix threading races on WebAudioSourceProviderImpl::provideInput

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 325 matching lines @@
 
     removeElementFromDocumentMap(this, &document());
 
     // Destroying the player may cause a resource load to be canceled,
     // which could result in userCancelledLoad() being called back.
     // Setting m_completelyLoaded ensures that such a call will not cause
     // us to dispatch an abort event, which would result in a crash.
     // See http://crbug.com/233654 for more details.
     m_completelyLoaded = true;
     m_player.clear();
+    if (audioSourceProvider())

[DaleCurtis, 2013/09/04 22:33:09]

Both of these need protection via #if ENABLE(WEB_AUDIO)

+        audioSourceProvider()->setClient(0);
 }
 
 void HTMLMediaElement::didMoveToNewDocument(Document* oldDocument)
 {
     LOG(Media, "HTMLMediaElement::didMoveToNewDocument");
 
     if (m_shouldDelayLoadEvent) {
         if (oldDocument)
             oldDocument->decrementLoadEventDelayCount();
         document().incrementLoadEventDelayCount();
@@ skipping 3091 matching lines @@
         updateActiveTextTrackCues(0);
 }
 
 void HTMLMediaElement::clearMediaPlayer(int flags)
 {
     removeAllInbandTracks();
 
     closeMediaSource();
 
     m_player.clear();
+    if (audioSourceProvider())
+        audioSourceProvider()->setClient(0);
     stopPeriodicTimers();
     m_loadTimer.stop();
 
     m_pendingActionFlags &= ~flags;
     m_loadState = WaitingForSource;
 
     if (m_textTracks)
         configureTextTrackDisplay();
 }
 
@@ skipping 514 matching lines @@
 {
     m_restrictions = NoRestrictions;
 }
 
 void HTMLMediaElement::mediaPlayerScheduleLayerUpdate()
 {
     scheduleLayerUpdate();
 }
 
 }