Merge "SurfaceFlinger: add more thread-safety annotations." am: be2ac15cea am: df92275f43

Original change: https://android-review.googlesource.com/c/platform/frameworks/native/+/2212955

Change-Id: I50970798f3d9c9a74eabf49408142a0f7cb5a919
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>