Do correct colorspace xform in asyncRescaleAndReadPixels in GPU impl.

When we're rescaling the conversion to the final colorspace happens during
the last rescaling draw. We were configuring the correct color space on
the final GrRenderTargetContext but not inserting a GrColorSpaceXform.

Bug: skia:8962
Change-Id: Iadcc0a8e438109ad4b74e7d2cf073ea157bfe236
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/217896
Auto-Submit: Brian Salomon <bsalomon@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Osman <brianosman@google.com>
1 file changed