Merge "Prevent crash when unregsiter the broadcast" into tm-dev am: d7e447b4

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17352123



Change-Id: I607ba3b6c0e5080d218ff8cd24a81f0826905ebe
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>