Jorge Castro announced the release of a Chrome extension called Chromify-OSD that makes the build-in Chrome notifications use NotifyOSD. I'll make this post short because for some reason the extension doesn't work for me in either Google Chrome or Chromium.
Reading the bug submissions, it seems the extension doens't work with Gmail notifications. But in my test it also didn't work with TweetDeck (so that means it works with... what? I don't know other extensions that provide notifications in Chrome but anyway) but maybe you have better luck with it.
Please note that the extension will ask for access to "all data on your computer and the websites you visit". That's normal, it's the only way NPAPI extension can work (extensions that can access stuff outside Chrome - like NotifyOSD).
Get the extension @ Chrome Web Store.