I'm curious as to why you are using Chrome and not Safari, when you have a Mac. Don't get me wrong, I can see some good reasons but there are also good reasons for using Safari.
*coughs* Firefox.
It's kinda strange. I can get in chat with Chromium on Windows, with Java 6.31, yet I can upgrade to 7.3. Could your version of Chrome be a little outdated and that may be the reason Java will not update? I'm sure curious about this one. I might need to ask a Mac user!
If you are up for an experiment, why not try Chromium for Mac?
http://www.macupdate.com/app/mac/36244/chromium
Fully security patched (better than Safari) and more secure than Chrome (no phone home).
As far as I know, there is a drawback with using more than one installation of a Chromium based browser on a Mac and that is that the profile gets shared. This may be a good thing and may not be. You may know better than I do here.