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chromium/chrome/test/data/extensions/api_test/mime_handler_view/test_sandboxed_frame.html 

<!doctype html>
<iframe id="sandbox1" src="testEmbedded.csv"
        sandbox="allow-scripts allow-same-origin"></iframe>
<iframe id="sandbox2" src="test_embedded.html"
        sandbox="allow-scripts allow-same-origin"></iframe>
<iframe id="notsandboxed" src="testEmbedded.csv"></iframe>
<script>
  function remove_frame(id) {
    document.getElementById(id).outerHTML = "";
  }
</script>