Always report SkImage_Gpu subclasses as being texture backed.

Change-Id: I1af002df1b07f04543b32add94bfdc0a016a338b
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/259284
Reviewed-by: Robert Phillips <robertphillips@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
2 files changed