Issue 3839 - Adapt for Prefs event changes

background.js

Index: background.js
===================================================================
--- a/background.js
+++ b/background.js
@@ -93,7 +93,15 @@
 
   modules.prefs = {
     Prefs: {
-      onChanged: new Notifier()
+      _listeners: Object.create(null),
+
+      on: function(preference, callback)

[Thomas Greiner, 2016/03/21 17:55:55]

What about extending `Notifier` instead so that `Notifier.addListener()` and
`Notifier.removeListener()` accept an optional name parameter at the first
position?

That way we could reuse it when we decide to migrate other APIs to the new
calling scheme. We'd also avoid duplicating some of the logic.

[Sebastian Noack, 2016/03/21 19:40:07]

Well, changing the calling convention of existing APIs across core and platform
is not the scope of this patch. However, we can move the this logic into a class
and use it under the hood to implement Notifier. Did that.

+      {
+        if (preference in this._listeners)
+          this._listeners[preference].push(callback);
+        else
+          this._listeners[preference] = [callback];
+      }
     }
   };
   var prefs = {
@@ -114,8 +122,11 @@
       set: function(value)
       {
         prefs[key] = value;
-        modules.prefs.Prefs.onChanged.triggerListeners(key);
-        return prefs[key];
+
+        var listeners = modules.prefs.Prefs._listeners[key];
+        if (listeners)
+          for (var i = 0; i < listeners.length; i++)
+            listeners[i]();
       }
     });
   });