Merge "Fix thread-safety issues with mRequestedNotificationListeners" into udc-dev am: ca08538c

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/22673942



Change-Id: I45ebb352355e5157111482524894170630418809
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>