add bench for drawAtlas

Bug: skia:
Change-Id: I00c86a99d3785eec67d9cc7dde31a7705e7d78cd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/203169
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Mike Reed <reed@google.com>
1 file changed