Mac: Fix Sierra solid color layer color-mismatch

Sierra treats the color correction of IOSurface-backed layers and solid
color layers differently. To ensure that behavior is consistent, do not
use solid color layers, rather, in such cases, use an 16x16 IOSurface
that is initialized to the solid color.

BUG=633805

Review-Url: https://codereview.chromium.org/2378423002
Cr-Commit-Position: refs/heads/master@{#421899}
2 files changed