Add lock to protect UnwantedInteractionBlocker am: a91d8576d9

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/native/+/18494314

Change-Id: Ib1b095125462ce02855ecd62c915915fe55648f2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>