Revert of Pass task runners to AudioManager constructor.

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 <AudioUnit/AudioUnit.h>
 #include <CoreAudio/AudioHardware.h>
 #include <stddef.h>
 #include <list>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "media/audio/audio_manager_base.h"
 #include "media/audio/mac/audio_device_listener_mac.h"
 
 namespace media {
 
 class AUAudioInputStream;
 class AUHALStream;
 
 // Mac OS X implementation of the AudioManager singleton. This class is internal
 // to the audio output and only internal users can call methods not exposed by
 // the AudioManager class.
 class MEDIA_EXPORT AudioManagerMac : public AudioManagerBase {
  public:
-  AudioManagerMac(
-      scoped_refptr<base::SingleThreadTaskRunner> task_runner,
-      scoped_refptr<base::SingleThreadTaskRunner> worker_task_runner,
-      AudioLogFactory* audio_log_factory);
+  AudioManagerMac(AudioLogFactory* audio_log_factory);
 
   // Implementation of AudioManager.
+  scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() override;
+  scoped_refptr<base::SingleThreadTaskRunner> GetWorkerTaskRunner() override;
   bool HasAudioOutputDevices() override;
   bool HasAudioInputDevices() override;
   void GetAudioInputDeviceNames(AudioDeviceNames* device_names) override;
   void GetAudioOutputDeviceNames(AudioDeviceNames* device_names) override;
   AudioParameters GetInputStreamParameters(
       const std::string& device_id) override;
   std::string GetAssociatedOutputDeviceID(
       const std::string& input_device_id) override;
 
   // Implementation of AudioManagerBase.
@@ skipping 66 matching lines @@
 
  protected:
   ~AudioManagerMac() override;
 
   AudioParameters GetPreferredOutputStreamParameters(
       const std::string& output_device_id,
       const AudioParameters& input_params) override;
 
  private:
   void InitializeOnAudioThread();
+  void ShutdownOnAudioThread();
 
   int ChooseBufferSize(bool is_input, int sample_rate);
 
   // Notify streams of a device change if the default output device or its
   // sample rate has changed, otherwise does nothing.
   void HandleDeviceChanges();
 
   scoped_ptr<AudioDeviceListenerMac> output_device_listener_;
 
+  scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
+  scoped_ptr<base::Thread> worker_thread_;
+
   // 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_;
 
   // Helper class which monitors power events to determine if output streams
   // should defer Start() calls.  Required to workaround an OSX bug.  See
   // http://crbug.com/160920 for more details.
   class AudioPowerObserver;
   scoped_ptr<AudioPowerObserver> power_observer_;
 
-  // Tracks all constructed input and output streams.
-  // TODO(alokp): We used to track these streams to close before destruction.
-  // We no longer close the streams, so we may be able to get rid of these
-  // member variables. They are currently used by MaybeChangeBufferSize().
-  // Investigate if we can remove these.
+  // Tracks all constructed input and output streams so they can be stopped at
+  // shutdown.  See ShutdownOnAudioThread() for more details.
   std::list<AudioInputStream*> basic_input_streams_;
   std::list<AUAudioInputStream*> low_latency_input_streams_;
   std::list<AUHALStream*> output_streams_;
 
   DISALLOW_COPY_AND_ASSIGN(AudioManagerMac);
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_MAC_AUDIO_MANAGER_MAC_H_