Code review comment for lp://staging/~joetalbott/qa-dashboard/add_xorg_desktop_column

The only issue I possibly see is that we are only doing xorg+plumbing on ImageMachineAgg... This makes it to where we can't display this on the raw data chart. If needed, we *could* do the math on the fly, though as we have found out in the past that isn't a very good way of doing things. Or people could just do the addition in their head? Or we could add it to ImageResult.