Sixth small fragment from "Reduce dependence on GrSurface's origin field" TBR=bsalomon@google.com Change-Id: I585ab16767c2276974763213916f25755c1a8a45 Reviewed-on: https://skia-review.googlesource.com/25743 Reviewed-by: Robert Phillips <robertphillips@google.com> Commit-Queue: Robert Phillips <robertphillips@google.com>