[skshaper] Add per-line callback


Bug: skia:
Change-Id: Iaaf7e95230207bc796dd436a918722a089426e34
Reviewed-on: https://skia-review.googlesource.com/c/190220
Commit-Queue: Ben Wagner <bungeman@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
4 files changed