It would be useful to have a preferences module that can be used in the model, view, and controller as necessary.

This factors out the `Prefs` object from UnifiedComplete.js into UrlbarPreferences.jsm and makes required changes so it's not tied to consts and other identifiers local to UnifiedComplete.js. It adds another new module, UrlbarUtils.jsm, for storing consts that both UrlbarPreferences and UnifiedComplete use. In order to preserve blame as much as possible, I used `hg cp` to copy UnifiedComplete.js to UrlbarPreferences.jsm, and then I removed all the non-Prefs code before making other changes, so this patch looks bigger than it really is. (Maybe I wasn't actually so successful in preserving a lot of blame.)

Comment on attachment 9008268 [details] Bug 1489282 - Create a UrlbarPreferences module that can be used across all urlbar components Marco Bonardo [::mak] has approved the revision.

Pushed by dwillcoxon@mozilla.com: https://hg.mozilla.org/integration/autoland/rev/67f7bbfb61c2 Create a UrlbarPreferences module that can be used across all urlbar components r=mak