chromium/src/third_party/blink/web_tests/http/tests/misc/resources/iframe-big.html - manifest_repos/chromium_src - Git at Google

 <!DOCTYPE html>
 <p>need something shows here.</p>
 <p style="position: absolute; left: 1000px; top: 1000px;">make the iframe big enough</p>

 <script>
 window.addEventListener('message', (event) => {
   event.source.postMessage({}, '*');
 });
 </script>
	<!DOCTYPE html>
	<p>need something shows here.</p>
	<p style="position: absolute; left: 1000px; top: 1000px;">make the iframe big enough</p>

	<script>
	window.addEventListener('message', (event) => {
	event.source.postMessage({}, '*');
	});
	</script>