Bug 785225 - Part 1: Don't rely on Engines singleton in AddonsReconciler; r=rnewman

services/sync/modules/addonsreconciler.js

@@ -20,7 +20,6 @@
 const Cu = Components.utils;
 
 Cu.import("resource://services-common/log4moz.js");
-Cu.import("resource://services-sync/engines.js");
 Cu.import("resource://services-sync/util.js");
 Cu.import("resource://gre/modules/AddonManager.jsm");
 
@@ -119,8 +118,6 @@ function AddonsReconciler() {
   let level = Svc.Prefs.get("log.logger.addonsreconciler", "Debug");
   this._log.level = Log4Moz.Level[level];
 
-  Svc.Obs.add("weave:engine:start-tracking", this.startListening, this);
-  Svc.Obs.add("weave:engine:stop-tracking", this.stopListening, this);
   Svc.Obs.add("xpcom-shutdown", this.stopListening, this);
 };
 AddonsReconciler.prototype = {
@@ -301,8 +298,7 @@ AddonsReconciler.prototype = {
    * This is typically called automatically when Sync is loaded.
    */
   startListening: function startListening() {
-    let engine = Engines.get("addons");
-    if (!engine || !engine.enabled || this._listening) {
+    if (this._listening) {
       return;
     }
 

services/sync/modules/engines/addons.js

@@ -657,6 +657,10 @@ function AddonsTracker(name) {
 AddonsTracker.prototype = {
   __proto__: Tracker.prototype,
 
+  get engine() {
+    return Engines.get("addons");
+  },
+
   get reconciler() {
     return Engines.get("addons")._reconciler;
   },
@@ -689,11 +693,16 @@ AddonsTracker.prototype = {
   observe: function(subject, topic, data) {
     switch (topic) {
       case "weave:engine:start-tracking":
+        if (this.engine.enabled) {
+          this.reconciler.startListening();
+        }
+
         this.reconciler.addChangeListener(this);
         break;
 
       case "weave:engine:stop-tracking":
         this.reconciler.removeChangeListener(this);
+        this.reconciler.stopListening();
         break;
     }
   }