GitLab

Also rename it to "image". No intended behavior change.
Part of supporting hidpi favicons in the tab strip.

BUG=138550
TBR=joi

Review URL: https://chromiumcodereview.appspot.com/10832128

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@149874 0039d316-1c4b-4281-b951-d872f2087c98