Revert "Revert "Plumb GrBackendTexture throughout skia.""

Revert "Revert "Plumb GrBackendTexture throughout skia.""

This reverts commit 7fa5c31c2c9af834bee66d5fcf476e250076c8d6.

Reason for revert: Relanding this change now that other fixes have landed.

Original change's description:
> Revert "Plumb GrBackendTexture throughout skia."
>
> This reverts commit 7da62b9059f3c1d31624a0e4da96ee5f908f9c12.
>
> Reason for revert: fix android roll
>
> Original change's description:
> > Plumb GrBackendTexture throughout skia.
> >
> > Bug: skia:
> > Change-Id: I1bae6768ee7229818a83ba608035a1f7867e6875
> > Reviewed-on: https://skia-review.googlesource.com/13645
> > Commit-Queue: Greg Daniel <egdaniel@google.com>
> > Reviewed-by: Robert Phillips <robertphillips@google.com>
> >
>
> TBR=egdaniel@google.com,bsalomon@google.com,robertphillips@google.com,brianosman@google.com,reviews@skia.org,stani@google.com
> NOPRESUBMIT=true
> NOTREECHECKS=true
> NOTRY=true
>
> Change-Id: I5cb8763cc837c83ebc6d10366fe2dd3efe35fb89
> Reviewed-on: https://skia-review.googlesource.com/13773
> Reviewed-by: Stan Iliev <stani@google.com>
> Commit-Queue: Stan Iliev <stani@google.com>
>

TBR=egdaniel@google.com,bsalomon@google.com,robertphillips@google.com,reviews@skia.org,brianosman@google.com,stani@google.com
# Not skipping CQ checks because original CL landed > 1 day ago.

Change-Id: I92bc074e4fe37fa5c83186afadc472c03802e8f2
Reviewed-on: https://skia-review.googlesource.com/13975
Reviewed-by: Greg Daniel <egdaniel@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>