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

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

Change-Id: I52586273362f452a9a9957d84cca8a4bb25af8b3