Treat GrTextureAdjusters mip copy like other producers, i.e. no fallback.

This makes sure that when we are not using repeat mode the colorType of
the producer will match the colorType of the returned proxy.

Bug: chromium:1044862
Change-Id: I9627517c383ff7c3e9801da21ddafdacfb747871
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/266218
Reviewed-by: Brian Osman <brianosman@google.com>
Commit-Queue: Greg Daniel <egdaniel@google.com>
2 files changed