Google on Tuesday said that it has bought Songza, a free online streaming music service that recommends tunes based on what people might be in the mood to hear. Were thrilled to announce that were becoming part of Google, Songza said on its website. Songza added that no immediate changes were planned for the free service, other than making it faster, smarter, and even more fun to use. It has applications tailored for mobile devices powered by Apple or Google-backed Android software.