--- a/accessible/src/jsat/Utils.jsm
+++ b/accessible/src/jsat/Utils.jsm
@@ -15,17 +15,17 @@ XPCOMUtils.defineLazyModuleGetter(this, 
   'resource://gre/modules/Geometry.jsm');
 XPCOMUtils.defineLazyModuleGetter(this, 'Roles',
   'resource://gre/modules/accessibility/Constants.jsm');
 XPCOMUtils.defineLazyModuleGetter(this, 'Events',
   'resource://gre/modules/accessibility/Constants.jsm');
 XPCOMUtils.defineLazyModuleGetter(this, 'Relations',
   'resource://gre/modules/accessibility/Constants.jsm');
 
-this.EXPORTED_SYMBOLS = ['Utils', 'Logger', 'PivotContext', 'PrefCache'];
+this.EXPORTED_SYMBOLS = ['Utils', 'Logger', 'PivotContext', 'PrefCache', 'SettingCache'];
 
 this.Utils = {
   _buildAppMap: {
     '{3c2e2abc-06d4-11e1-ac3b-374f68613e61}': 'b2g',
     '{ec8030f7-c20a-464f-9b0e-13a3a9e97384}': 'browser',
     '{aa3c5121-dab2-40e2-81ca-7ea25febc110}': 'mobile/android',
     '{a23983c0-fd0e-11dc-95ff-0800200c9a66}': 'mobile/xul'
   },
@@ -769,8 +769,41 @@ PrefCache.prototype = {
         Logger.logException(x);
       }
     }
   },
 
   QueryInterface : XPCOMUtils.generateQI([Ci.nsIObserver,
                                           Ci.nsISupportsWeakReference])
 };
+
+this.SettingCache = function SettingCache(aName, aCallback, aOptions = {}) {
+  this.value = aOptions.defaultValue;
+  let runCallback = () => {
+    if (aCallback && aOptions.callbackNow) {
+      aCallback(aName, this.value);
+      if (aOptions.callbackOnce) {
+        runCallback = () => {};
+      }
+    }
+  };
+
+  let settings = Utils.win.navigator.mozSettings;
+  if (!settings) {
+    runCallback();
+    return;
+  }
+
+
+  let lock = settings.createLock();
+  let req = lock.get(aName);
+
+  req.addEventListener('success', () => {
+    this.value = req.result[aName] == undefined ? aOptions.defaultValue : req.result[aName];
+    runCallback();
+  });
+
+  settings.addObserver(aName,
+                       (evt) => {
+                         this.value = evt.settingValue;
+                         runCallback();
+                       });
+};