device/bluetooth: Add I/O watcher for audio data retrieval triggered by state change.

device/bluetooth/bluetooth_audio_sink.h

 // Copyright 2014 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 DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_H_
 #define DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_H_
 
 #include <stdint.h>
 #include <string>
 #include <vector>
@@ skipping 55 matching lines @@
         BluetoothAudioSink* audio_sink,
         BluetoothAudioSink::State state) = 0;
 
     // Called when the volume of the BluetoothAudioSink object is changed.
     // |audio_sink| indicates the object being changed, and |volume| indicates
     // the new volume level of that object.
     virtual void BluetoothAudioSinkVolumeChanged(
         BluetoothAudioSink* audio_sink,
         uint16_t volume) = 0;
 
-    // TODO(mcchou): Add method to monitor the availability of audio data during
-    // the streaming. This method should associate with BluetoothAudioSink
-    // specific IOBuffer wrapping fd, read_mtu and write_mtu.
+    // Callled when there is audio data available. |audio_sink| indicates the

[armansito, 2015/03/12 03:42:55]

nit: Called

[Miao, 2015/03/12 22:33:32]

Done.

+    // object being changed. |data| is the pointer to the audio data and |size|
+    // is the number of the bytes in |data|.

[armansito, 2015/03/12 03:42:55]

I would explain here that this method provides the raw audio data which hasn't
been processed or assembled in any way and that the RTP units and SBC decoding
needs to happen here.

[armansito, 2015/03/12 03:42:55]

nit: s/number of the bytes/number of bytes/

[Miao, 2015/03/12 22:33:31]

Done.

+    virtual void BluetoothAudioSinkDataAvailable(BluetoothAudioSink* audio_sink,
+                                                 char* data,
+                                                 size_t size) = 0;
   };
 
   // The ErrorCallback is used for the methods that can fail in which case it
   // is called.
   typedef base::Callback<void(ErrorCode)> ErrorCallback;
 
   // Possible volumes for media transport are 0-127, and 128 is used to
   // represent invalid volume.
   static const uint16_t kInvalidVolume;
 
@@ skipping 24 matching lines @@
   // unregistered even if the user applications fail to do so.
   virtual ~BluetoothAudioSink();
 
  private:
   DISALLOW_COPY_AND_ASSIGN(BluetoothAudioSink);
 };
 
 }  // namespace device
 
 #endif  // DEVICE_BLUETOOTH_BLUETOOTH_AUDIO_SINK_H_