Update: I wasn’t aware but now I know that the extension works for Chrome and everything Chromium-based equally well.
Just put together a simple extension for Chrome and company to share any page through an active Google+ account. Just install it and look for the “+” icon in the address bar. Clicking on it brings a popup that loads the official button with the counter and everything.
Please note that sharing is possible for public pages only. For private pages you’ll probably see an error from G+. Enjoy.
Bug reports and suggestions are welcome!