Chrome bug, got malware or did I did I break it?
I just had the same thing - the extension which was broken for me was one called Join Tabs... Dodgy!
I had the same problem and it turned out to be the extension "Web RSS Subscriber" that was to blame.
Apparently some extensions in Google Chrome, includying old and obsolete ones, have been hacked. If you are having the problem stated in the OP, please follow these steps and add the extension that causes the trouble to the list.
Known extensions that have been hacked:
Inkognito Tab Switch 2.2
Web RSS Subscriber
Steps to find out the rotten extensions:
Disable all your extensions. Options->Settings->Extensions
Enable the first one. Open a webpage where you have had the same problem, and check if it happens now.
If it happens, add that extension to the list. If it doesn't happen, disable that extension and repeat for the next extension.