Merge "Notify window manager service that we are switching users" into rvc-dev am: 12b5186f am: 5b380adb am: d25b02fe

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

Change-Id: I39a791dbe982f39ebc96ddb38626088295c4e2ad