Update GrLumaColorFilterEffect to use a child FP.

We are updating FPs to receive their input via a child FP where
possible, instead of relying on the input color.

Change-Id: I377fbf676185caa8c8a5b60b7a58bf98dc6d4da7
Bug: skia:10217
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/295078
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: John Stiles <johnstiles@google.com>
4 files changed