Reland "Remove GrBackendObject and all related functions from Skia."

This is a reland of ccd4cfc23ebbbecbc6b292359352aad335ad7b73

Original change's description:
> Remove GrBackendObject and all related functions from Skia.
> 
> Bug: skia:
> Change-Id: I59434b7477c0bc26fd982bd81eb97ab94bbba073
> Reviewed-on: https://skia-review.googlesource.com/125822
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> Commit-Queue: Greg Daniel <egdaniel@google.com>

Bug: skia:
Change-Id: Ibd1b9bd04b36840d9d872e2f0970dd6bac378bc9
Reviewed-on: https://skia-review.googlesource.com/129380
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
31 files changed