gm: add some overrides

Change-Id: I5348e2da1a2034b629d43b9e9faadb6db333abe8
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/228348
Commit-Queue: Hal Canary <halcanary@google.com>
Reviewed-by: Ben Wagner <bungeman@google.com>
19 files changed