AudioManagerBase: Create and run the audio thread lazily.

media/audio/mock_audio_manager.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_MOCK_AUDIO_MANAGER_H_
 #define MEDIA_AUDIO_MOCK_AUDIO_MANAGER_H_
 
 #include "base/macros.h"
 #include "media/audio/audio_manager.h"
 
@@ skipping 32 matching lines @@
       const std::string& device_id) override;
 
   media::AudioOutputStream* MakeAudioOutputStreamProxy(
       const media::AudioParameters& params,
       const std::string& device_id) override;
 
   media::AudioInputStream* MakeAudioInputStream(
       const media::AudioParameters& params,
       const std::string& device_id) override;
 
-  scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() const override;
+  scoped_refptr<base::SingleThreadTaskRunner> GetTaskRunner() override;
   scoped_refptr<base::SingleThreadTaskRunner> GetWorkerTaskRunner() override;
 
   void AddOutputDeviceChangeListener(AudioDeviceListener* listener) override;
   void RemoveOutputDeviceChangeListener(AudioDeviceListener* listener) override;
 
   AudioParameters GetDefaultOutputStreamParameters() override;
   AudioParameters GetOutputStreamParameters(
       const std::string& device_id) override;
   AudioParameters GetInputStreamParameters(
       const std::string& device_id) override;
   std::string GetAssociatedOutputDeviceID(
       const std::string& input_device_id) override;
 
   scoped_ptr<AudioLog> CreateAudioLog(
       AudioLogFactory::AudioComponent component) override;
 
  protected:
   ~MockAudioManager() override;
 
  private:
   scoped_refptr<base::SingleThreadTaskRunner> task_runner_;
 
   DISALLOW_COPY_AND_ASSIGN(MockAudioManager);
 };
 
 }  // namespace media.
 
 #endif  // MEDIA_AUDIO_MOCK_AUDIO_MANAGER_H_