AudioTrack: new transfer mode for Java offload support

New transfer mode for java AudioTrack using offload
  path, where data is provided through the write method,
  and the callback is used to notify the track owner
  more data can be written on the track.

Bug 86837964
Test: adb shell clof --source /sdcard/Music/my.mp3

Change-Id: I47c760b7fb8f1431945ca24ff4a26311b63cb761