switch over to no lockPixels in pixelref

Bug: skia:6481
Change-Id: I7c32d2e6dcd4c9cd8aa761ac5c4794c916eb650a
Reviewed-on: https://skia-review.googlesource.com/13193
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Leon Scroggins <scroggo@google.com>
Reviewed-by: Matt Sarett <msarett@google.com>
Commit-Queue: Mike Reed <reed@google.com>
9 files changed