I added the code I had for a Mirror API-based Google glass app:
This is based on the original Mirror API, not the GDK API. I think the latter is better for barcode scanning in the end since it's on-device. For that reason I probably won't do anything more with the Mirror version, and am not sure it works since I don't have a device. But it is simple, probably 90% right, and should get the job done on any Glass device when it does work.
So, probably should be considered almost deprecated from the moment it's committed, unless someone takes it up and runs with it, but wanted to put it out there for anyone who is interested.