nonwebby-scheme-in-form-submitted.https.html

<!DOCTYPE html>
<html>
<body onload="test()">
<p>
    This tests that forms with non-webby actions can be submitted. The
    test passes if the form submits successfully.
</p>
<form action="nonwebbyscheme://mixed-content-warning-should-appear"></form>
<script>
function test() {
  if (window.testRunner) {
    testRunner.dumpAsText();
    testRunner.waitForPolicyDelegate();
    document.getElementsByTagName("form")[0].submit();
  }
}
</script>
</body>
</html>

chromium/third_party/blink/web_tests/http/tests/security/mixedContent/nonwebby-scheme-in-form-submitted.https.html