I have Chrome open (Yosemite 10.1) and there are 7 instances of Google Chrome Helper running. There is a single tab open in the browser. I have 3 extensions installed AND running (1Password, JSON Formatter, and Postman).
Chrome has been a big problem for a while. Different builds have been really solid or really leaky and "crashy". This build (40.0.2214.45 beta (64-bit)) seems pretty unstable. Of course, I see the (beta) tag now and am wondering how to get to a stable release. Maybe that's my issue?