Merge "Add FLAG_IMMUTABLE to PendingIntents" am: a3aa817aa5 am: b119c3792c am: fc609be986

Original change: https://android-review.googlesource.com/c/platform/development/+/2229375

Change-Id: I3e9728301a903e8bfc687c01fd815f5999e0d287
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>