Indicate client process during streaming rebuffering

Change-Id: I199eb3bbbe398ef442dd03290c89592efb39dae4
 - Audio was not playing after buffering done during streaming
   of audio-video playback
 - Changed to indicate to client process that the track was disabled
   because of underrun.
 - It will then automatically call start() when data is available
CRs-Fixed: 491525