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

media/audio/mac/audio_manager_mac.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_
 #define MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_
 
 #include <CoreAudio/AudioHardware.h>
 #include <string>
 
@@ skipping 38 matching lines @@
 
   static bool GetDefaultOutputChannels(int* channels);
 
   static bool GetDeviceChannels(AudioDeviceID device,
                                 AudioObjectPropertyScope scope,
                                 int* channels);
 
   static int HardwareSampleRateForDevice(AudioDeviceID device_id);
   static int HardwareSampleRate();
 
+  // Notify streams of a device change if the default output device or its
+  // sample rate has changed, otherwise does nothing.
+  void HandleDeviceChanges();
+
  protected:
   virtual ~AudioManagerMac();
 
   virtual AudioParameters GetPreferredOutputStreamParameters(
       const AudioParameters& input_params) OVERRIDE;
 
  private:
   bool HasUnifiedDefaultIO();
 
   // Helper methods for constructing AudioDeviceListenerMac on the audio thread.
   void CreateDeviceListener();
   void DestroyDeviceListener();
-  void HandleDeviceChanges();
 
   scoped_ptr<AudioDeviceListenerMac> output_device_listener_;
 
   // Track the output sample-rate and the default output device
   // so we can intelligently handle device notifications only when necessary.
   int current_sample_rate_;
   AudioDeviceID current_output_device_;
 
   AggregateDeviceManager aggregate_device_manager_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerMac);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_