Merge "Add a guard on UserController to avoid user switches when not ready."...

Merge "Add a guard on UserController to avoid user switches when not ready." into rvc-dev am: 340e55d0 am: cd5d29a7 am: f1fe4119 am: c91eaada

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

Change-Id: I0853ae8e6936b258d5d5b97539a529aa74990735