In GPU CanvasKit, default to sRGB surfaces

Change-Id: I1931b09e6a4a52fb7d91a0d3f013e1d0519919dd
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/487977
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Brian Osman <brianosman@google.com>
3 files changed