sales on the condition that (A) the buyer or lessee not deal with the competitors of the seller or lessor ("exclusive dealings") or (B) the buyer also purchase another different product ("tying") but only when these acts substantially lessen competition (Act Section 3, codified at 15 U.S.C. 14);
Here Google isn't doing A(exclusive dealings). They are allowing other peoples apps on the phone. They allow competing search and location providers. They just require that Google be the default. They are "tying" different product together. It is possible to argue that this substantially lessens competition.