Implement SkColorSpace struct traits in skia.mojom.ImageInfo.

Completes the skia mojom struct traits implementation for ImageInfo by
using Skia's built-in SkColorSpace::serialize() functionality. This
allows for exact SkColorSpaces to be efficiently transmitted, alongside
things like SkBitmaps, through mojo message pipes.

Later work to improve color space management in Chromium will depend on
this change. (See crbugs for examples.)

Bug: 758057, 809385
Change-Id: I1193f81c727d8663370fd6fd802edd9dd397abff
Reviewed-on: https://chromium-review.googlesource.com/c/1357633
Reviewed-by: Robert Sesek <rsesek@chromium.org>
Reviewed-by: Chris Palmer <palmer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#615611}
6 files changed