By Liana B. Baker LAS VEGAS (Reuters) – Sony Corp will begin testing a new television service that combines traditional viewing with on-demand content through its PlayStation gaming system, a cloud-based service could possibly change long-established cable and media industry relationships. Sony executives described the as-yet unnamed service on Tuesday as a blend of live cable, on-demand and DVR content. Speaking at the Consumer Electronics Show in Las Vegas, they promised an intuitive design for searching for content – addressing a common complaint of cable customers. Sonys embryonic effort builds on similar moves by Microsoft Corp and Intel Corp. Viewers could buy viewing packages through Sony, much as customers now do through cable operators like Comcast.