Comcast may soon allow customers using its cloud-connected X1 cable box system to buy games from Electronic Arts through their televisions, according to five sources briefed on the plans. Such a partnership would come as the cable company seeks to protect its turf against a new wave of challengers. After two years of testing, Comcast and EA, are close to reaching an agreement to stream video games such as “FIFA” and “Madden,” into the living rooms of some of Comcast’s more-than 22 million customers across the United States, said the sources, who declined to speak publicly before a deal had been struck. Comcast would make the games available on X1, a video operating system with apps and an interface that is considered the most sophisticated in the cable industry, the sources said. It features Internet applications, viewing recommendations and voice control.