SurfaceFlinger: protect state members in Layer

Add proper locking to protect state members in Layer.
These members are accessed by both the main thread and binder.

Bug: 119481871
Test: SurfaceFlinger unit tests
Test: go/wm-smoke
Change-Id: I12d47711992e09c0677b77f7e1b36c1254b63a1b
15 files changed