WPT details: Web platform tests test H1 connection reuse, but they don't test other features. * DNS cache: Not currently possible to test. * H2/H3 connection sharding: Chrome doesn't support these with WPT. * ALPN cache: Not testable. * Reporting/NEL: These are draft specs, and a different solution is likely to be used long term, making Chrome's implementation non-standard. All current WPT tests do pass with partitioning enabled, however. * SSL/QUIC session resumption cache: Not possible to test.
Partition network state by the network partition key (which consists of top frame site and possibly frame site), to protect against cross-site tracking through the use of side channels. "Network State" here includes connections (H1, H2, H3, websocket), the DNS cache, ALPN/H2 support data, TLS/H3 resumption information, Reporting/NEL configuration and uploads, and Expect-CT information. Explainer: https://github.com/MattMenke2/Explainer---Partition-Network-State/blob/main/README.md
Cross-site tracking is a major privacy concern for users. This is a necessary part of addressing the problem.
Explainers: https://github.com/MattMenke2/Explainer---Partition-Network-State/blob/main/README.md