Advanced URL Shortener add-on for Google Docs lets you to shorten multiple long URLs in your document by a click. Long URLs are shortened to goog.gl short URLs.

Free Features:
 - Shorten a single link at a time

Pro Features:
 - Bulk processing to shorten multiple links in a click
 - Shorten by retaining link text
 - View analytics report of each short URL
 - Download and extract URLs from the document without shortening