A mural featuring David Alan Grier, host of “Chocolate News.”

D. L. Hughley's program on CNN was canceled.

Characters from “The Cleveland Show,” coming on Fox.

LOS ANGELES — On the eve of Barack Obama’s election last fall as the first African-American president, television seemed to be leaning toward a post-racial future. In October two prominent cable networks — CNN and Comedy Central — began new programs that featured black hosts, a development that was notable because so few current programs on cable or broadcast channels have minority leads.