We have many APIs that are device-agnostic, but we only build or enable them for b2g. For example, activities and alarms. That's fine because many of these are sensitive and require frontend interaction to grant privileges. We should start this process for the Firefox FE, but that's a separate line of work. Here, we should build "desktop" support into gecko for as many as we can and make them easily (though also safely) enable-able. The desktop b2g builds can enable them by default, as we already do for apps etc. I think we already have enable-able apps and mediastorage, which is awesome. Next up on my list would be system messages, navigation policies, tcpsocket, alarm, contacts, activities, though not necessarily in that order. We can settle on a final list at the same time we work out the details for bug 846113.