f6d0fc190c
Added a keyguardVisibilityChanged callback to indicate when the keyguard is covered by something (alarm, phone, etc). Face unlock doesn't start if it's not visible and it restarts appropriately when it gains visibility again. This mostly fixes b/7362774 and b/7376783, but there's some jank when face unlock goes away (if it was interrupted while running). Change-Id: I7bdf8ef6af687acaa7152d8e61bfdcc1979259ff