It is no need to take any action to set up a measurement sharing via Google+ network - Google Analytics measures all actions of its own social network natively.
All actions are tracked with method
_trackSocial. It is possible to view all tracked values in panels "Standard reporting" -> "Audience" -> "Social" in Google Analytics.
You can use a plugin GA debug for Chrome to view tracked parameters. You can also share this site by clicking the "+1" button in the right column.