add subpixel tweaking

Bug: skia:
Change-Id: Ibf5fdf00694e29cb3f3268ea577a8d317e6c7614
Reviewed-on: https://skia-review.googlesource.com/c/193697
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
Auto-Submit: Mike Reed <reed@google.com>
1 file changed