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

<!DOCTYPE html>
<html>
<head>
<title>Check that the referrer header is correct</title>
</head>
<body>
<div id="console"></div>
<script>
  var log = document.querySelector("#console");
  var result;
  if (document.referrer == "")
    result = "FAIL: no referrer";
  else if (document.referrer.indexOf(".html") !== -1)
    result = "FAIL: referrer contains more than just the origin";
  else
    result = "PASS";
  log.innerText = result;
  document.title = result;
</script>
</body>
</html>