Add nil input color space to canvas blob creator tests.

Because Skia drawing assumes sRGB for null colorspace images
tests should not expect equality between encoded and color-converted
images with null colorspaces.

Bug: 901677
Change-Id: If82a212d085b228b5cec9fad4ef891f4dec53cbc
Reviewed-on: https://chromium-review.googlesource.com/c/1379108
Commit-Queue: Aaron Krajeski <aaronhk@chromium.org>
Reviewed-by: Fernando Serboncini <fserb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#622931}
4 files changed