clean up after big refactor of SkColorFilter --> ...Base

Change-Id: I67ba7db1a1e4e0c8deb5299a6580a669cc08f38c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/299056
Reviewed-by: John Stiles <johnstiles@google.com>
Commit-Queue: Mike Reed <reed@google.com>
6 files changed