Oilpan: Don't destruct HRTFDatabaseLoader::m_thread during a sweeping phase

Source/modules/webaudio/AudioContext.cpp

 /*
  * Copyright (C) 2010, 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 181 matching lines @@
     m_destinationNode->uninitialize();
 
     if (!isOfflineContext()) {
         ASSERT(s_hardwareContextCount);
         --s_hardwareContextCount;
     }
 
     // Get rid of the sources which may still be playing.
     derefUnfinishedSourceNodes();
 
+    ASSERT(m_listener);
+    m_listener->waitForHRTFDatabaseLoaderThreadCompletion();
+
     m_isInitialized = false;
     clear();
 }
 
 void AudioContext::stop()
 {
     // Usually ExecutionContext calls stop twice.
     if (m_isStopScheduled)
         return;
     m_isStopScheduled = true;
@@ skipping 661 matching lines @@
 
     for (HashSet<AudioNode*>::iterator k = m_deferredCountModeChange.begin(); k != m_deferredCountModeChange.end(); ++k)
         (*k)->updateChannelCountMode();
 
     m_deferredCountModeChange.clear();
 }
 
 } // namespace blink
 
 #endif // ENABLE(WEB_AUDIO)