With the iTunes’ banner waving supremely over the digital music landscape, Google continues to build its own music service, CNET has learned. According to multiple music industry sources, Google could launch a music service that offers song downloads and streaming music as early as this fall. Google has already signaled that it wishes to give users of phones equipped with Google’s Android operating system a better music offering. At Google’s I/O conference last month, the search engine offered attendees a demonstration of a web-based iTunes competitor. Also TechCrunch reported two weeks ago that it discovered a “Google Music” logo hosted on Google’s domain…