Reimplement the AlsaPcmOutputStream and fix the threading issues.

media/audio/audio_output.h

-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2008-2009 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_AUDIO_OUTPUT_H_
 #define MEDIA_AUDIO_AUDIO_OUTPUT_H_
 
 #include "base/basictypes.h"
 
 // Low-level audio output support. To make sound there are 3 objects involved:
 // - AudioSource : produces audio samples on a pull model. Implements
@@ skipping 24 matching lines @@
 // or WMA. Complex format decoding should be done by the renderers.
 
 
 // Models an audio stream that gets rendered to the audio hardware output.
 // Because we support more audio streams than physically available channels
 // a given AudioOutputStream might or might not talk directly to hardware.
 class AudioOutputStream {
  public:
   enum State {
     STATE_CREATED = 0,  // The output stream is created.
-    STATE_OPENED,       // The output stream is opened.
     STATE_STARTED,      // The output stream is started.
     STATE_PAUSED,       // The output stream is paused.
     STATE_STOPPED,      // The output stream is stopped.
-    STATE_CLOSING,      // The output stream is being closed.
     STATE_CLOSED,       // The output stream is closed.
     STATE_ERROR,        // The output stream is in error state.
   };
 
   // Audio sources must implement AudioSourceCallback. This interface will be
   // called in a random thread which very likely is a high priority thread. Do
   // not rely on using this thread TLS or make calls that alter the thread
   // itself such as creating Windows or initializing COM.
   class AudioSourceCallback {
    public:
@@ skipping 99 matching lines @@
   // Get AudioManager singleton.
   // TODO(cpu): Define threading requirements for interacting with AudioManager.
   static AudioManager* GetAudioManager();
 
  protected:
   virtual ~AudioManager() {}
 };
 
 
 #endif  // MEDIA_AUDIO_AUDIO_OUTPUT_H_