chromium/android_webview/test/data/fetch-echo.html

<!doctype html>
<html>
<head><title>running</title></head>
<body><script>
window.onload = function () {
  const params = new URL(document.location).searchParams;
  fetch(params.get('url')).then(e => e.text()).then(text => document.title = text);
};
</script></body>
</html>