If you like to tweak your Chrome install, check out:
chrome://flags/#extension-active-script-permission
It adds an extra level of permission where each extension that doesn't ask for a specific website is, by default, locked out of every website, and you have to enable it manually by either clicking on it, whitelisting the websites where it can run or globally (example pic, sorry for not being in english: http://puu.sh/q5QFR/d6004da3bb.png)