This has been a long time coming, but starting Tuesday, Chrome users on Windows will only be able to install extensions from Google’s own Chrome Web Store. Google argues that this is meant to keep malicious extensions — which are often installed from third-party sites — in check. Users who have already installed extensions from third-party sites may find that they have been disabled and cannot be re-enabled or re-installed. The only way to get them back up and running is by installing them through the Chrome Web Store (assuming the developer has made them available there). Google first announced its plans for this move last November. At the time, it told developers who were hosting their extensions themselves to migrate to the Web Store as soon as possible.