Rename first-party-only cookies to same-site cookies.

As per https://tools.ietf.org/html/draft-west-first-party-cookies-05 and
https://lists.w3.org/Archives/Public/ietf-http-wg/2016JanMar/0134.html.

BUG=459154

Review URL: https://codereview.chromium.org/1615773005

Cr-Commit-Position: refs/heads/master@{#372630}
28 files changed