This page attempts to detect uBlock origin in Chrome by probing for chrome-extension://cjpalhdlnbpafiamejdnhcphjbkeiagm/web_accessible_resources/noop.html and observing timing differences in comparison to a fake extension. It should work even if you have the extension disabled for the page.

This technique is impossible in firefox because firefox extensions' web_accessible_resources are of the format moz-extension://<extension-UUID>/images/my-image.png where the extension-UUID is randomly generated for every browser instance in order to prevent fingerprinting.