Merge "Send system user broadcasts in headless system user mode." into tm-qpr-dev am: 8c72c3c907 am: 7e62e4aff6

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/20965081

Change-Id: Ibe8b15f7ce07e9c117ee331dd2da5f9b17a61ab2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>