Fix frontOfTask assignment.

If all activities of a given stack were finishing, no activity was
marked as front-of-task. This confused ActivityManager, so make sure
there's always exactly one activity marked as front-of-task.

Change-Id: I087cbe10280d4a60aa5ccfaefe24a223523fb3f2
change default for unknown sources & verify apps

Change-Id: I04467c0c1ef3985b416f6e58013ddc3ce4137712
Keyguard: disable music transport control debug

Change-Id: Ia4361d0850334dc0944559c40409c9062cf02e47