Use the suggested stream if it's currently active

This makes the MediaSessionService check if the suggested stream is active
when dispatching a volume event and prefer it to a remote session if it is.
This mostly affects apps that use Activity.setVolumeControlStream.

bug:18318480
Change-Id: Ib8825394bf7a223fbd92bcb2c3ecb7c596ce7c29
1 file changed