<!DOCTYPE html>
<head>
  <script>
    window.onmessage = function(e) {
      if (e.data == "start_test") {
        document.getElementById('link').click();
        location.href = "{{location[server]}}/content-security-policy/navigate-to/support/spv-test-iframe3.sub.html";
      }
    }
    window.addEventListener('securitypolicyviolation', function(e) {
      top.postMessage({iframe: 'iframe1', violatedDirective: e.violatedDirective}, '*');
    });
  </script>
</head>

<body>
  <a href="{{location[server]}}/content-security-policy/navigate-to/support/delayed_frame.py" id="link" target="iframe2">dummy link</a>
  IFRAME 1
</body>