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>
31 files changed