It looks homemade. My guess is that would be used to carry nails or such, much like one of those bags fron Lowe's or Home Depot you can tie around your waste today. Those compartments don't look big enough for tools, so I'd think probably more to keep nails or fittings organized yet mobile.
My first thought was something for a farrier (someone who shoes horses). They don't use many tools so they could build something pretty specialized to keep them organized, but those compartments don't look big enough for their knife, rasps, and hammer. It could be for general use or maybe someone specialized. I just don't know, but that was probably in an old chicken coop just because it was a good dry place to store it, not necessarily because it has anything to do with chickens.