chromium/chrome/test/data/service_worker/fetch_from_page.html

<!doctype html>
<title>Fetch url specified by a query param</title>
<script>
async function fetch_from_page(url) {
  try {
    const response = await fetch(url);
    return await response.text();
  } catch (error) {
    return `${error}`;
  }
}
</script>