[graphite] Add Sampler caching

Bug: skia:13118
Change-Id: I84510b026d82e9c205340a28ead91329e643c83d
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/566565
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
2 files changed