“The first phase, dubbed “Phase 0,” will see Google proxying requests only to its own domains using a proprietary proxy. This will help Google test the system’s infrastructure and buy more time to fine-tune the domain list.”
Chrome’s IP Protection hides your address from third-party trackers by routing their traffic through a proxy. Phase 0 proxies only Google’s own domains, through Google’s proxy, with access tokens from a Google authentication server that sets each user’s quota. A second hop run by an outside CDN is only something Google is “considering.” Every other ad network loses your IP. Google keeps it.