Codebase Browser
chromium
Go to App

chromium/third_party/blink/web_tests/http/tests/inspector-protocol/resources/security-origin-testpage.html 

<html>
<body>
<div id="rootDiv">Root div text</div>
<iframe src="https://devtools.test:8443/inspector-protocol/resources/test-page.html"></iframe>
</body>
</html>