Move process* closures into the GrTextBlob

Change-Id: I8614a7d267940ec5f000ffdb50833ce50c0df774
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/197850
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Herb Derby <herb@google.com>
2 files changed