I like the idea! I use a bench top grinder, the Oregon 620, and because of that, I never sharpen using files on the bar out in the woods anymore.
My dull chains go into an old metal coffee can, the sharp ones goes onto a nail hanging near the grinder.
My property is small enough that when I go out cutting, if I need to swap chains, I just go back to the shop and do it on my work bench. However, carrying a spare chain is something I've done from time to time. Never thought about using a locker. I just pile it up on the floor board of my tractor with the wedges and wrench.
Good idea though!