AppShell uses
  --load-apps: to provide the list of apps to load
and automatically launches (only) the first one in that list.

Chrome uses:
  --load-apps: to load a list of apps
  --load-and-launch-app: to load and launch one app

Chrome's behavior makes more sense, and consistency is nice. --load-and-launch-app lives in //apps, so we don't even need to move anything out of Chrome.