Makes the Metal backend more consistent with the other backends,
and allows new init parameters to be added without significantly
changing API.
Added updated sk_cf_obj because I needed some of its functionality.
Bug: skia:10804
Change-Id: I6f1dd1c03ddc4c4b702ea75eff14bc0f98ab5ad2
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/334426
Commit-Queue: Jim Van Verth <jvanverth@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
351c9b53d6