Merge "User switcher: hooks up broadcast receivers." into tm-qpr-dev am: ec9b5b0d

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/20339874



Change-Id: Id8c44ed8ba416457a3b22991a53f10639dded6c8
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>