Google Chrome on GNU/Linux infected by extension
It is freeware (free as in "a filthy beer bottle with drowned insects inside") I removed this as soon as I identified it as the probable culprit -- and so far, no more Shopping Assistant.
The odd thing is that Shopping Assistant only activated upon visiting certain sites and, amazingly, a site for a local Indian Restaurant (India Jewel in Kenmore NY) seems to be one (hacked server?)
It's malware alright; mostly an annoyance that renders the browser nearly unusable by opening up various new pages (windows or tabs) when clicking almost anywhere on the current page, and so I am calling it Annoyware. But because you have no control over what sites are loaded and some will be malicious, it is more serious.
The icon for the contaminated extension does I think look [like this: images.wondershare.com/images/icon/chrome-youtube-downloader.jpg] (http://images.wondershare.com/images/icon/chrome-youtube-downloader.jpg)
A page at Malware Tips has an image showing some of what Shopping Assistant looks like. Anyhow you'll know it if you are infected, I think.