chromium/chrome/test/data/popup_blocker/check-sessionstorage.html

<!DOCTYPE html>
<html>
<head>
<title>
  Check that the session storage namespace of the parent is not accessible
</title>
</head>
<body>
<div id="console"></div>
<script>
  var log = document.querySelector("#console");
  var result;
  if (sessionStorage.getItem("key") == "set")
    result = "FAIL: popup can access session storage namespace";
  else
    result = "PASS";
  log.innerText = result;
  document.title = result;
</script>
</body>
</html>