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: 1fb1d40c am: e99727c2

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

Change-Id: I9f2f8fd8fe80bfa2ffcb6370a10f6dcf83ca1c91