Dismiss keyguard when user button is tapped

When multi-user is disabled and user button is tapped
on the keyguard, the contact app is displayed behind the keyguard.
The keyguard should be dismissed when the contact app is launched.

Change-Id: I7daa0bec84b5172e78668cc71e51955f166ede0a
(cherry picked from commit 0a334053)