So the novelty in this game is 10.Bg5, although I note that the move has actually been played at least once before by Raetsky. I took a look in Wojo's Weapons, Hilton's and Ippolito's new book, and unsurprisingly they don't cover the move (at least not that I found). That book focuses very much on the Catalan. They give 9.O-O O-O, and then refer to 10.b4!? as one of the "great mysteries" of the line. Please note this isn't criticism; it's hardly the aim of the book to go to the depth one would expect of Super GMs battling for the WC. In the end, it doesn't appear that 10.Bg5 is particularly ground breaking.