Notify the system of all remote volume changes

If a volume change occurred because it was sent through the MediaController directly
it wasn't showing the system's volume UI. This fixes things so the volume slider gets
shown for all volume requests with the SHOW_UI flag set.

bug:19036130
Change-Id: I1f7cb2e03386e2f3f7bc448cb4c38a71573775ff
2 files changed