Partway through writing a small browser extension last year, and realizing how much access they have to everything you look at, I stopped using all but a couple trusted browser extensions. Seriously, it was like 15 lines of code to take a screenshot of whatever page you're looking at and send it to a server every 2 seconds with no indication that anything is happening.
Granted, you have to accept a permissions dialog, but most extensions ask for way too many permissions. That cloud-to-butt extension? It already has all the permissions it needs to send the text on every page to a database somewhere, and unless you carefully audit the source of every extension you install (obviously google isn't), you'd never notice, you're just trusting some extension author.