Using Google+ interactive post for web pages
A Google+ interactive post is similar to a basic share post but adds a call-to-action button to the post. In a product post for example, the call-to-action button can be "Add to cart", engaging your users direct from Google+ stream. The call-to-action button appears just below the main post area. Aside from the call-to-action, the interactive post will ask for user permission the first time the share button is used through the standard Google+ OAuth consent dialog or always depending on the value of data-approvalprompt attribute.