(Reuters) – Yahoo Inc has bought Blink, a mobile messaging startup that lets users send messages that self-destruct and control who sees their messages and for how long. The deal comes just days after rival messaging startup Snapchat settled charges with U.S. regulators that accused it of deceiving consumers by promising that photos sent on its service disappeared forever after a certain period of time. Yahoo Chief Executive Marissa Mayer has been stepping up the companys efforts to build online services for the smartphones and tablets that consumers increasingly use to access the Web. Yahoo has acquired several small, mobile start-ups since Mayer took over.