Add test for the GrContext::createCompressedBackendTexture API

Bug: skia:9680
Change-Id: Ib51613e6bacb36ff59b2e1e3c3cf13221d0382fa
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/261083
Commit-Queue: Robert Phillips <robertphillips@google.com>
Reviewed-by: Greg Daniel <egdaniel@google.com>
2 files changed