bucketmouse, you're not crazy. This just happened to me the other day.
I updated to the latest version of CCleaner and ended up with Chrome installed, too. No checkbox, no asking me first, nothing.
From reading the other comments above, it sounds like somebody needs to go back to COS 101 and learn how to write an installer that works. Installing 3rd-party programs without consent or notification is the definition of malware.