Reduce read/write-SurfacePixels call sites

Change-Id: I657c489c56b93765567be69076fb4c3d526e55a5
Reviewed-on: https://skia-review.googlesource.com/13068
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Robert Phillips <robertphillips@google.com>
4 files changed