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: 5b380adb am: d25b02fe am: 7a36a5f5

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

Change-Id: I5b41275b1449245ff9fff712887b9c34d72f50fd