Reuse GrTexture instances when the same GrBackendTexture is used to
repeatedly fulfill a promise SkImage.

Bug: skia:8613

Change-Id: I35c76435d630d2daa034e0c3efb59666bfd6882a
Reviewed-on: https://skia-review.googlesource.com/c/175820
Commit-Queue: Brian Salomon <bsalomon@google.com>
Reviewed-by: Robert Phillips <robertphillips@google.com>
20 files changed