Revert 290359 "Remove AudioBuffersState class."

trunk/src/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"
 
 // Low-level audio output support. To make sound there are 3 objects involved:
 // - AudioSource : produces audio samples on a pull model. Implements
 //   the AudioSourceCallback interface.
 // - AudioOutputStream : uses the AudioSource to render audio on a given
 //   channel, format and sample frequency configuration. Data from the
 //   AudioSource is delivered in a 'pull' model.
 // - AudioManager : factory for the AudioOutputStream objects, manager
 //   of the hardware resources and mixer control.
@@ skipping 31 matching lines @@
 
 class MEDIA_EXPORT AudioOutputStream {
  public:
   // 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 MEDIA_EXPORT AudioSourceCallback {
    public:
     // Provide more data by fully filling |dest|.  The source will return
-    // the number of frames it filled.  |total_bytes_delay| contains current
-    // number of bytes of delay buffered by the AudioOutputStream.
+    // the number of frames it filled.  |buffers_state| contains current state
+    // of the buffers, and can be used by the source to calculate delay.
     virtual int OnMoreData(AudioBus* dest,
-                           int total_bytes_delay) = 0;
+                           AudioBuffersState buffers_state) = 0;
 
     // There was an error while playing a buffer. Audio source cannot be
     // destroyed yet. No direct action needed by the AudioStream, but it is
     // a good place to stop accumulating sound data since is is likely that
     // playback will not continue.
     virtual void OnError(AudioOutputStream* stream) = 0;
 
    protected:
     virtual ~AudioSourceCallback() {}
   };
@@ skipping 89 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_