chromium/third_party/blink/web_tests/http/tests/inspector-protocol/network/resources/page-with-subresource.html

<!-- For testing subresource blocking in blocked-by-client-network-observer.js;
     this page references a subresource which will be blocked in the test.
     The image doesn't exist so this would 404 but it doesn't matter because
     blocking happens before the resource gets fetched anyway. -->
<html><body><img src=to-be-blocked.jpg></body></html>