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

<!DOCTYPE html>
<title>Plugin starting with TEXT/HTML</title>
<object data="about:blank" type="text/html"></object>
<script>
  var object = document.querySelector("object");
  window.addEventListener("load", init);

  function init() {
    let href = window.location.href;
    const token  = "?test_data=";
    let query_index = href.indexOf(token);
    let test_data = null;
    if (query_index !== -1) {
      test_data = href.substr(query_index + token.length).split(",");
    }

    if (test_data) {
      let test_command =
          `${test_data[0]}('${test_data.splice(1).join("','")}');`;
      window.eval(test_command);
    }
  }

  // Returns true if |w| is cross-origin with |window|.
  function is_cross_origin(w) {
    let result = false;
    try {
      w.location.origin;
    } catch(e) {
      result = true;
    }
    return result;
  }

  // Navigates <object> to |cross_origin_url|. Then sets the object type to
  // "text/csv" and triggers a MimeHandlerView creation. The test succeeds if
  // the MHV extension is loaded.
  function test_cross_origin_frame(cross_origin_url, csv_url) {
    object.data = cross_origin_url;
    object.onload = () => {
      if (!is_cross_origin(window[0]))
        return;
      object.type = "text/csv";
      object.data = csv_url;
    };
  }

  // Navigates the <object> to |cross_origin_url| and after a very short timeout
  // sets the object type and source to "text/csv". The test succeeds if the
  // MHV extension is loaded.
  function test_navigation_race_embedder(cross_origin_url, csv_url) {
    object.data = cross_origin_url;
    window.setTimeout(() => {
      object.type = "text/csv";
      object.data = csv_url;
    }, 0);
  }

  // Navigates the object to some cross-origin content which then navigates it
  // self to another location passed through the query. After the load event,
  // the <object> is set to render a MimeHandlerView. This would lead to a
  // navigation race: the browser will try to navigate the content frame to
  // 'about:blank' while the cross-process renderer triggers its own navigation.
  // The test succeeds when the MHV extension is loaded.
  function test_navigation_race_cross_origin(cross_origin_url,
                                             other_cross_origin_url,
                                             csv_url) {
    object.data = `${cross_origin_url}?next=${other_cross_origin_url}`;
    object.onload = () => {
      if (!is_cross_origin(window[0]))
        return;
      if (object.data === csv_url)
        return;
      object.type = "text/csv";
      object.data = csv_url;
    };
  }
</script>