A single instance of NotificationPlayer will play notifications
back-to-back, and was, for each requesting AudioFocus. But as
a new notification was about to be played, its accompanying
thread was terminated, and the completion listener was never
called, and therefore AudioFocus was not released (e.g. two
requests for one release).
The fix consists in requesting AudioFocus only once and
abandonning it when the only reported completion is received.
Added a FIXME note about a better solution to be implemented.
Bug 7680947
Change-Id: Ica9d5c1eb5d57c89ceebe66282af69f0f7d43667
6313cbe1d0