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: 527c14b4 am: e099401e am: efe55329

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

Change-Id: I2d47080a41e27aa907a7a533138e9b61f7183865