Get PulseAudio implementation working.

media/audio/audio_io.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_AUDIO_IO_H_
 #define MEDIA_AUDIO_AUDIO_IO_H_
 
 #include "base/basictypes.h"
 #include "media/audio/audio_buffers_state.h"
 #include "media/base/audio_bus.h"
@@ skipping 72 matching lines @@
     // plugins. In any case, data is usually immediately available,
     // so there would be no delay.
     virtual void WaitTillDataReady() {}
 
    protected:
     virtual ~AudioSourceCallback() {}
   };
 
   virtual ~AudioOutputStream() {}
 
-  // Open the stream. false is returned if the stream cannot be opened.
+  // Open the stream. false is returned if the stream cannot be opened.  Open()
+  // must always be followed by a call to Close() even if Open() fails.

[scherkus (not reviewing), 2012/10/11 20:19:31]

this makes me sad considering we return true/false :|

[DaleCurtis, 2012/10/12 00:09:12]

Yeah, it's not ideal.  At least the comment codifies the behavior all of our
existing streams rely on.

   virtual bool Open() = 0;
 
   // Starts playing audio and generating AudioSourceCallback::OnMoreData().
   // Since implementor of AudioOutputStream may have internal buffers, right
   // after calling this method initial buffers are fetched.
   //
   // The output stream does not take ownership of this callback.
   virtual void Start(AudioSourceCallback* callback) = 0;
 
   // Stops playing audio. Effect might not be instantaneous as the hardware
@@ skipping 70 matching lines @@
   // Sets the Automatic Gain Control (AGC) state.
   virtual void SetAutomaticGainControl(bool enabled) = 0;
 
   // Returns the Automatic Gain Control (AGC) state.
   virtual bool GetAutomaticGainControl() = 0;
 };
 
 }  // namespace media
 
 #endif  // MEDIA_AUDIO_AUDIO_IO_H_