Here’s an unexpected pairing: Calvin “Snoop Dogg” Broadus and 3D (real name: Robert Del Naja) from Massive Attack have teamed up to create “Calling Mumia,” a new track that fuses Snoop’s flow with the smooth, stoner-y trip-hop beats that made Massive Attack famous. The song features on the soundtrack to the documentary “In Prison My Whole Life,” which played at this year’s Sundance Festival. The film tells the story of Mumia Abu-Jamal, a former Black Panther who is currently serving a life sentence for the murder of a Philadelphia police officer.