These AudioTrack operations are relatively expensive Binder calls (and
will soon be even more expensive to fix a deadlock at AudioTrack::start),
and they were being called excessively. Now AudioTrack start, stop,
and pause are only called when there is an actual play state change.
Details:
- distinguish ATTR_TRANSPORT vs. ATTR_PLAY_STATE for audio players
- android_audioPlayer_setPlayState is only called when the play state changes
- handler_AudioPlayer_transport is only called for transport changes other than play state
- android_audioPlayer_setPlayState is always called with mutex locked
- since media player currently only handles play state, handler_MediaPlayer_transport
is still called for both ATTR_TRANSPORT and ATTR_PLAY_STATE
- since the handlers for ATTR_BQ_ENQUEUE and ATTR_ABQ_ENQUEUE are only called if in
state PLAYING, changed an "if" to an "assert"
Change-Id: Iee2968fd98d215885b7105053bb1604f962ea337