Google announced a number of changes that will affect brand extensions in the Chrome browser. Since June 12, the new extensions become available only from the online store Chrome Web Store.
Since 2011, the developers could use so-called inline installation, which allowed to install extensions directly from the site without entering into the official Chrome store.
Now Google is gradually negate this opportunity, first, for the new extensions. And September 12, 2018 inline-installation will cancel and existing extensions. Instead, the developer can place on your website a button that, when clicked, users will be automatically redirected to Chrome Web Store. Since the beginning of December 2018 API for such installation will be removed from your browser with the release of Chrome 71.