On what would the browser user base their decision? If an extension injects an icon into the DOM of the page, then the resulting `img` tag needs to put somethi

On what would the browser user base their decision? If an extension injects an icon into the DOM of the page, then the resulting `img` tag needs to put something in its `src`. The extension author may choose to use the `data:` scheme, but that's a development-time decision.