third_party/blink/web_tests/http/tests/security/mixedContent/redirect-http-to-https-script-in-iframe.html - chromium/src - Git at Google

 <html>
 <body>
 <script>
 if (window.testRunner) {
     testRunner.dumpAsText();
     testRunner.overridePreference("WebKitAllowRunningInsecureContent", true);
 }
 </script>
 <p>This test loads a secure iframe that loads an insecure script (but with a
 tricky redirect).  We should trigger a mixed content callback because an active
 network attacker could have redirected the script load to
 https://attacker.com.</p>
 <iframe src="https://127.0.0.1:8443/security/mixedContent/resources/frame-with-redirect-http-to-https-script.html";
 ></iframe>
 </body>
 </html>
	<html>
	<body>
	<script>
	if (window.testRunner) {
	testRunner.dumpAsText();
	testRunner.overridePreference("WebKitAllowRunningInsecureContent", true);
	}
	</script>
	<p>This test loads a secure iframe that loads an insecure script (but with a
	tricky redirect). We should trigger a mixed content callback because an active
	network attacker could have redirected the script load to
	https://attacker.com.</p>
	<iframe src="https://127.0.0.1:8443/security/mixedContent/resources/frame-with-redirect-http-to-https-script.html";
	></iframe>
	</body>
	</html>