Removed the brand-color related APIs.

The chromium uses themem-color APIs now, remove the unused brand-color's.

BUG=383941
NOTRY=true

Review URL: https://codereview.chromium.org/391783004

git-svn-id: svn://svn.chromium.org/blink/trunk@178128 bbb929c8-8fbe-4397-9dbb-9b2b20218538