clean up code: explicits, finals, and namespace

Change-Id: Ie346a2dab7648e28e71ed0b6fd9331895644f1a1
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/441400
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Herb Derby <herb@google.com>
1 file changed