Convert 'CookieOptions::first_party_url' to a 'url::Origin'.

We don't need a full URL for any check we're doing inside //net, so let's
throw away the bits we don't need, and make the origin check explicit
(rather than matching the URLs that result from 'GURL::GetOrigin()').

BUG=459154

Review URL: https://codereview.chromium.org/1413623002

Cr-Commit-Position: refs/heads/master@{#354999}
6 files changed