chromium/third_party/blink/renderer/core/testing/data/frameserializer/frames/top_frame.html

<!-- This page is used to test that the FrameSerializer correctly retrieves
     the expected resources when dealing with iframes.
-->
<html>
<body>

<!-- Images in a frame should be serialized -->
<iframe src="top.png"></iframe>

<!-- Resources used by an iframe tag, serialize once -->
<iframe src="simple_iframe.html"></iframe>
<iframe src="simple_iframe.html"></iframe>

<!-- Object tags can be used to create iframes -->
<object data="object_iframe.html"></object>

<!-- Embed tags can be used to create iframes as well -->
<embed src="embed_iframe.html"></object>

<!-- Encodings are respected and normalization is not performed -->
<iframe src="encoded_iframe.html"></iframe>

</body>
</html>