Try not to let the AUHAL driver get stuck sending silence.

media/audio/mac/audio_auhal_mac.h

Index: media/audio/mac/audio_auhal_mac.h
diff --git a/media/audio/mac/audio_auhal_mac.h b/media/audio/mac/audio_auhal_mac.h
index d1eff8d9237a14aea9887048d6980413e48dd560..06421f8d585ae5c3d10d72409f2e577d1ac2a3d1 100644
--- a/media/audio/mac/audio_auhal_mac.h
+++ b/media/audio/mac/audio_auhal_mac.h
@@ -145,6 +145,8 @@ class AUHALStream : public AudioOutputStream {
   // The flag used to stop the streaming.
   bool stopped_;
 
+  bool notified_for_possible_device_change_;
+
   // The input AudioUnit renders its data here.
   scoped_ptr<uint8[]> input_buffer_list_storage_;
   AudioBufferList* input_buffer_list_;