Nice add-on, almost the one with code reading function. But does not read some QR codes easily readable by mobile apps. Few samples (links are temporal, please don't miss):

http://oi64.tinypic.com/i52frd.jpg
http://oi67.tinypic.com/2cfe5b5.jpg
http://oi64.tinypic.com/2mh687q.jpg

(you can check them online here for instance: https://zxing.org/w/decode.jspx )

Will amend this rating when problem is fixed.