A blocking call is necessary where we want to guarantee that
the player wont access the surface after the method call has
returned. We currently only do this for the case:
Surface->Null
But we should also do it for the case:
SurfaceA->SurfaceB
Since the caller may reasonably do something like destroy
SurfaceA immediately after it's been replaced.
-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=135921296
64262085a7