Keyguard now disables all navbar buttons when turning screen off
instead of only recents.
Navbar is told about screen off/on and disables the layout transition
animation on screen off - if the user quickly turns the screen back
on they do not see the end of the fade out animation.
Bug:7377776
Change-Id: I96a050d58c6c9ce8537f50408655006fadbfcd4f
1bbd49d72e