page_with_iframe_as_content_url.html

<html>

<head>
    <script>
        onmessage = function(e) {
            document.title = e.data;
        }
    </script>
</head>

<body>
  <iframe id='iframe_test_id' src="content://org.chromium.chrome.test.TestContentProvider/simple_iframe.html" >
  </iframe>
</body>

</html>

chromium/chrome/test/data/android/page_with_iframe_as_content_url.html