More features start using website setting to store per-origin data. Unlike with permission-y content settings, they don't need more widely scoped patterns.

This leads to conversions between ContentSettingsPattern and url::Origin (or more commonly GURL), such as:

GURL url = GURL(pattern.ToString());
DCHECK(url.is_valid());

WebsiteSettingsRegistry should offer a way to specify and enforce that a setting is origin-only. HostContentSettingsMap would then provide an interface to handle such settings without knowing about patterns. DCHECK-ing that no wider patterns are used would be done internally.