Allow taps to once again penetrate the darkness.

(Tapping on the lights out shadow will now immediately show
the system bar in addition to informing the StatusBarManager
that the system UI chrome should be shown. This allows an
ACTION_DOWN to reach the back/home/whatever buttons even if
it was originally invoked when the lights were out.)

Bug: 3400262
Change-Id: I9b1b5240c003ad510fd65cb606728850d705ef33