Share one thread between all AudioOutputControllers instead of creating one per stream.

media/audio/linux/alsa_output.h

 // Copyright (c) 2010 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.
 //
 // Creates an output stream based on the ALSA PCM interface.
 //
 // On device write failure, the stream will move itself to an invalid state.
 // No more data will be pulled from the data source, or written to the device.
 // All calls to public API functions will either no-op themselves, or return an
 // error if possible.  Specifically, If the stream is in an error state, Open()
@@ skipping 18 matching lines @@
 #define MEDIA_AUDIO_LINUX_ALSA_OUTPUT_H_
 
 #include <alsa/asoundlib.h>
 
 #include <string>
 
 #include "base/gtest_prod_util.h"
 #include "base/lock.h"
 #include "base/ref_counted.h"
 #include "base/scoped_ptr.h"
-#include "base/thread.h"
 #include "media/audio/audio_io.h"
+#include "media/audio/audio_manager_base.h"
 
 namespace media {
 class SeekableBuffer;
 };  // namespace media
 
 class AlsaWrapper;
 class AudioManagerLinux;
 
 class AlsaPcmOutputStream :
     public AudioOutputStream,
@@ skipping 194 matching lines @@
   MessageLoop* client_thread_loop_;
 
   // The message loop responsible for querying the data source, and writing to
   // the output device.
   MessageLoop* message_loop_;
 
   DISALLOW_COPY_AND_ASSIGN(AlsaPcmOutputStream);
 };
 
 #endif  // MEDIA_AUDIO_LINUX_ALSA_OUTPUT_H_