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

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

Change-Id: I4de02878efb868aaed416e05d90988aaec347905
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>