Merge "UMS use mUsersLock to synchronized" am: 659ccfc928 am: ca2d0638ab am: 897d3913fe

Original change: https://android-review.googlesource.com/c/platform/frameworks/base/+/1512949

MUST ONLY BE SUBMITTED BY AUTOMERGER

Change-Id: I99e976f1212b0226c43f39c6ccd30509c174bc33