CRONY,
a Comerade [in a Canting Sense.] Two or Three Rogues, who agree to beg or rob in Partnership, call one another Crony; as, Such a one is my Crony; as much as to say, He and I go Snacks.
Crony in the 1811 Vulgar Tongue
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).