Add a new class to group media/audio player features under one
interface. Currently only used for audio-related AppsOps
restrictions. In the future can group routing, audio focus
handling by the framework...
MediaPlayer inherits from PlayerBase, and overrides the methods
that are needed to delegate the handling of the restrictions
in a separate class.
When AppOps restrictions change (as triggered through the
callback in PlayerBase), reset the volume to its value intended
by the application (when unmuting) or the framework (0 when
enforcing the restriction).
Bug 28069414
Change-Id: I2f38e4b9b3c029778836868cf78f4d15d7603247
3c86a343df