Defer OSX output stream Start() around system supend and resume.

media/audio/mac/audio_auhal_mac.h

 // Copyright 2013 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.
 //
 // Implementation notes:
 //
 // - It is recommended to first acquire the native sample rate of the default
 //   output device and then use the same rate when creating this object.
 //   Use AudioManagerMac::HardwareSampleRate() to retrieve the sample rate.
 // - Calling Close() also leads to self destruction.
 // - The latency consists of two parts:
 //   1) Hardware latency, which includes Audio Unit latency, audio device
 //      latency;
 //   2) The delay between the moment getting the callback and the scheduled time
 //      stamp that tells when the data is going to be played out.
 //
 #ifndef MEDIA_AUDIO_MAC_AUDIO_AUHAL_MAC_H_
 #define MEDIA_AUDIO_MAC_AUDIO_AUHAL_MAC_H_
 
 #include <AudioUnit/AudioUnit.h>
 #include <CoreAudio/CoreAudio.h>
 
+#include "base/cancelable_callback.h"
 #include "base/compiler_specific.h"
 #include "base/synchronization/lock.h"
 #include "media/audio/audio_io.h"
 #include "media/audio/audio_parameters.h"
 
 namespace media {
 
 class AudioManagerMac;
 class AudioPullFifo;
 
@@ skipping 126 matching lines @@
   // Container for retrieving data from AudioSourceCallback::OnMoreIOData().
   scoped_ptr<AudioBus> output_bus_;
 
   // Dynamically allocated FIFO used when CoreAudio asks for unexpected frame
   // sizes.
   scoped_ptr<AudioPullFifo> audio_fifo_;
 
   // Current buffer delay.  Set by Render().
   uint32 current_hardware_pending_bytes_;
 
+  // Used to defer Start() to workaround http://crbug.com/160920.
+  base::CancelableClosure deferred_start_cb_;
+
   DISALLOW_COPY_AND_ASSIGN(AUHALStream);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_AUHAL_MAC_H_