Google Inc. is joining Citigroup Inc. and MasterCard Inc. to set up a mobile payment system that will turn Android phones into a kind of electronic wallet, Reuters reported, based on a story in The Wall Street Journal. The new technology would allow consumers to wave their Android phones in front of a small reader at the checkout counter to make payments. The planned payment system would allow Google to offer retailers more data about their customers and help them target advertisements and discount offers to mobile device users near their stores, sources told the Journal. Google is not expected to get a cut of the transaction fees, the paper said.