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.
+    // Called when there is audio data available. |audio_sink| indicates the
+    // object being changed. |data| is the pointer to the audio data and |size|
+    // is the number of bytes in |data|. This method provides the raw audio data
+    // which hasn't been processed, so RTP assembling and SBC decoding need to
+    // be handled in order to get PCM data.
+    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_