If updateLockscreenTimeout gets called before the Runnable queued
from lockNow gets executed, lockNow request will be ignored. Fix
this by not clearing out the runnable if it's pending lock request.
Test: Switch user, ensure lockscreen comes up
Bug: 161149543
Change-Id: Ie486396fd7328edf8ca0912df92524bb82a1fb7f
(cherry picked from commit 875fa991aa)
Merged-In: Ie486396fd7328edf8ca0912df92524bb82a1fb7f