Return correct GrBackendFormat when ycbcr conversion is valid.

Bug: skia:
Change-Id: Ieb24c0169a150c153a468fbbe9a8f60766516860
Reviewed-on: https://skia-review.googlesource.com/c/193698
Commit-Queue: Greg Daniel <egdaniel@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
1 file changed