Refactor image decoders to use 'colorSpace' instead of 'colorProfile'

This is a little bit more logical given that images (PNGs) can
encode color space information without actually using a color
profile.

This CL started as an attempt to improve support for these PNGs,
but I think it's useful to refactor first.

TBR=aelias@chromium.org
TBR=esprehn@chromium.org

BUG=

Review-Url: https://codereview.chromium.org/2454123002
Cr-Commit-Position: refs/heads/master@{#428237}
39 files changed