localstorage-about-blank-partitioned-win-open.html

<!doctype html>
<meta charset="utf-8">
<script src="./partitioning-utils.js"></script>
<script>
window.addEventListener("load", () => {
  localStorage.clear();

  const userID = getOrCreateID("userID4");
  const payload = {
    message: "window loaded",
    userID,
  }

  let win = window.opener ? window.opener : window.parent;
  win.postMessage(payload, "*");
});

window.addEventListener("message", e => {
  let win = window.opener ? parent.window.opener : window.parent;

  if (e.data.command == "open about:blank window") {
    window.blankWindow = window.open("about:blank");
    const payload = {
      message: "about:blank frame ID",
      userID: window.blankWindow?.localStorage["userID4"],
    }

    let win = window.opener ? parent.window.opener : window.parent;
    win.postMessage(payload, "*");
  }

  if (e.data.command == "close about:blank window") {
    window.blankWindow.close();
    win.postMessage({message: "about:blank window closed"}, "*");
  }
});
</script>

chromium/third_party/blink/web_tests/external/wpt/webstorage/resources/localstorage-about-blank-partitioned-win-open.html