By Alina Selyukh and Gerry Shih WASHINGTON/SAN FRANCISCO (Reuters) – Snapchat is known for an app that enables users to send photo messages that can vanish within seconds of being viewed. On Wednesday, company officials didnt even appear at a Capitol Hill hearing on data security theyd been invited to – and a top senator wasnt happy. Senate Commerce Committee Chairman Jay Rockefeller said Snapchat had declined his invitation to testify and insinuated that the Los Angeles-based company, which has disclosed massive data breaches within the past year, was concealing something.