Google Checkout is a gateway plugin that extends Jigoshop, allowing users to checkout with their Google Checkout account.
Google Checkout is a faster, more secure way to buy from stores across the web using a single username and password. Use it once and stop creating new accounts every time you buy.
Google’s fraud protection policy covers you against unauthorized purchases made through Google Checkout, and they don’t share your purchase history or full card number with sellers.
Please find documentation