LayoutTests/http/tests/security/mixedContent/resources/frame-with-insecure-frame.html

<script>
var frameDidLoad = false;

onload = function()
{
    if (window.opener)
        window.opener.postMessage(frameDidLoad ? 'done' : 'blocked', '*');
}
</script>
<iframe onload="frameDidLoad = true"
        src="http://127.0.0.1:8080/security/mixedContent/resources/boring.html"></iframe>