Merge "Add explicit <mutex> include" into main am: 716c482c88 am: 74b2cd03b5

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/3459703

Change-Id: I1a14da5007dc4463e2a7369c3cc34afcc43185ca
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>