Update Metal PipelineStateCache to use new stats tracking

Change-Id: I3edc1812f74319abeb13d94cf7e2426bd68b57a3
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/382282
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
3 files changed