Fix writePixels of sRGB data to legacy GPU surface

Adjusted unit test to verify this behavior.

Bug: skia:6547 chromium:713632 chromium:713702
Change-Id: I6240937b2faf6ccb6adfc9477dc85ae961cdbbb7
Reviewed-on: https://skia-review.googlesource.com/14279
Commit-Queue: Brian Osman <brianosman@google.com>
Reviewed-by: Brian Salomon <bsalomon@google.com>
2 files changed