According to the Engadget article on the story, Google has also filed a patent application which gives us a small insight into the software service that Google will be providing. Apparently, Google will act "as a third-party broker" that receives the transaction information from customers that place orders using their device. The service can allow customers to select certain options such as what kind of shipping, as well as other options, and provides the consumer with the total bill
The service would then collect the payment, shipment address, and then forward all that information to the seller in order to finalize the purchase. One downside for advocates of consumer privacy will be that Google's system appears to give companies the ability to see what consumers are buying and know whether age-specific advertising was resulting in real-world sales for the targeted audience. This would give Google more accurate data on consumer spending behavior.
Image from Engadget