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

Source/modules/webaudio/AudioContext.cpp

Index: Source/modules/webaudio/AudioContext.cpp
diff --git a/Source/modules/webaudio/AudioContext.cpp b/Source/modules/webaudio/AudioContext.cpp
index c1d45883a7f99bd9e34b01772d072da9836b246e..c813e0e6c1c595be28b4dfd87749eca2b0d12de6 100644
--- a/Source/modules/webaudio/AudioContext.cpp
+++ b/Source/modules/webaudio/AudioContext.cpp
@@ -199,6 +199,9 @@ void AudioContext::uninitialize()
     // Get rid of the sources which may still be playing.
     derefUnfinishedSourceNodes();
 
+    ASSERT(m_listener);
+    m_listener->waitForHRTFDatabaseLoaderThreadCompletion();
+
     m_isInitialized = false;
     clear();
 }