O, right. That's Chrome. If you right click on a page in Chrome and select Inspect Element it will open the dev tools. Then you clikc the button bottom right of Chrome, and another box pops up. Near the top left of that, there's an "overrides" link, which brings up that list of user agents.
I doubt such a tool is very accurate, but better than nothing, I guess. Remember to return to the normal setting afterwards, anyhow.