Merge "Add a guard on UserController to avoid user switches when not ready." into rvc-dev am: 340e55d091 am: 527c14b4cc am: 4a2578f4d2 am: a51e5d9201

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11817081

Change-Id: I96b08ae6b0bdbbe186c9732e3499cef94350944d