AudioTrack: fix head position after restore

The head position transfered to the new track
by restoreTrack_l() must take into account the frames that
are dropped from the old track to avoid a non recoverable
offset in the playback head position returned to applications.

Bug: 11230062.
Change-Id: I51143a08b95e8f264ed709ae2054360315f2b8b1
3 files changed