Reintroduces the play/pause rebuffering logic we eliminated
in JB zero day to fix double spins and slow startup - but
activates that logic only based on a comparison of the
current bandwidth measurement and the lowest bitrate track
in the movie.
Needs to be submitted with related changes in /frameworks/av
bug: 7230071
Change-Id: Ib3859a961bd3901a9c4df01eeab2b8b75f49aefe