Making Face Unlock fix that wasn't proerly merged in master

It appears that https://android-git.corp.google.com/g/#/c/144795/1
was incorrectly merged down into master.  This commit is to correctly
add the change from that cl into the master branch.

Without this change, if you bring up the emergency dialer while Face
Unlock is running, you momentarily see the backup lock.

Change-Id: I6350150bf46ac52d5c50c9e88119f09397d22902