Merge "Notify window manager service that we are switching users" into rvc-dev...

Merge "Notify window manager service that we are switching users" into rvc-dev am: 12b5186f am: 69a5697e am: ec40f07e am: fb7f7598

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/11821052

Change-Id: Ib5426bc09a61156498749f1a1c5c487f06d2dbd1