Add GrResourceProviderPriv and expose GrGpu in it

Bug: skia:
Change-Id: Iad965ecf33c9dc75c4f068d547698d973f52eb94
Reviewed-on: https://skia-review.googlesource.com/91440
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
3 files changed