Rated 3 out of 5 stars

Why would people intentionally send all their (confidential or not) docs to Google so that they will be sent back to be read on their home machine? Are we to believe that a copy does not remain at Google Inc and used by Google? Have you read Google's new code of privacy? -- It says that they can collate information from all their sources including all the docs you send to them through this viewer.

This review is for a previous version of the add-on (1.8.1-signed.1-signed). 

I hope you understand that what being passed to Google are ONLY URLs but never the content itself, and that these URLs must be publicly accessible. Those URLs that require authentication will inherently bar Google from downloading the files and transforming them to the Docs format.
<br>So, the only leakages possible are some private URLs of which their access require no authentication. Should you instead blame those people who think private URLs are secure, given that proxies and phishing url checkers are so widely deployed in our Web?