chromium/chrome/test/data/printing/selection_iframe.html

<html>

<body>
    <p>
      A page with a selection containing an iframe. The browser should be
      able to print it.
    </p>

    <div id="selection-start"></div>
    An iframe here: <iframe src="/simple.html"></iframe>
    <div id="selection-end"></div>

    <script>
        var range = document.createRange();
        range.setStart(document.getElementById("selection-start"), 0);
        range.setEnd(document.getElementById("selection-end"), 0)
        window.getSelection().addRange(range);
    </script>
</body>

</html>