This extension uses Google URL Shortener service to give you a shortened version of the current tab's URL.
When the Extension icon is clicked, it pulls the URL of the tab that is open, and then shortens it using Google URL Shortener service. The shortened URL can be copied into the browser's clipboard so that it can be pasted elsewhere, or a QR Code of the URL can be generated.
For more information about the Google URL Shortener API, refer to this link: https://developers.google.com/url-shortener/