I just made an account to add to this thread. Avast update installed Chrome on my machine without giving me an option as well. After clicking on the update button I was not presented with any other options and after rebooting to finish the installation I had Google Chrome installed and set as my default browser.
There was absolutely no option for whether to install Chrome or not for me. I'm not some computer illiterate who doesn't know how to use the custom install options, I was not given an option at all.
In reply to schmidthouse, as far as it being a "small thing" to get bent out of shape over, I have installed this software on over 20 machines for people who don't know how to use computers and now I will have to visit every one of them to uninstall Chrome when they call me asking why their browser doesn't have their bookmarks or their normal homepage anymore.
Thanks a lot Avast!
EDITED to seem less like an attack on schmidthouse, that was not my intention but it read that way initially.