convert sample completely to SkM4

Change-Id: Ib8fdf0f9c326f0809d132da650eaccc20e58f9f8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/266676
Reviewed-by: Mike Reed <reed@google.com>
Commit-Queue: Mike Reed <reed@google.com>
3 files changed