SurfaceView: Ensure the Surface remains valid with SurfaceHolder#lockCanvas

Fixes an issue where the surface was destroyed while the caller had a
valid Surface. The SurfaceHolder#lockCanvas API states the
Surface remains valid until the caller unlocks the canvas. This cl
ensures the validity by acquiring the mSurfaceLock before changing
the state of the Surface.

Test: app in b/234006724 does not ANR
Test: app in b/235188096 does not crash
Test: atest SurfaceViewTest
Bug: 235188096
Change-Id: I67ae2b98b83cc148128bb7c70cf2180c927c0b04