Move all SubtitleTrack operations to TimeProvider's event handler thread. Bug: 28784397 Change-Id: Iff848635390e99ffb19add03277a9d62feece4cc
Move all SubtitleTrack operations to TimeProvider's event handler thread. Bug: 28784397 Change-Id: Iff848635390e99ffb19add03277a9d62feece4cc