Google announced a comprehensive shopping cart that could soon be available across the search giant’s app ecosystem. The forthcoming Universal Cart may change how shoppers think about checking out. Merchants and consumers generally expect a direct relationship between a cart and an ecommerce site. Amazon’s shopping cart might be an exception. Like all marketplace shopping carts, it can hold products from any number of third-party sellers, but it remains a single cart associated with a single ecommerce site. Google’s announcements on May 19 suggest that this one-to-one association may not continue. Google I/O Specifically, Google introduced three commerce-related features during I/O, its premiere developer conference. Universal Cart is persistent and AI-powered, following shoppers across Google properties and tracking products, offers, and prices, ultimately completing transactions. Universal Commerce Protocol is expanding checkout across markets and channels while extending into categories beyond retail.…