From a740be31b3c2c8312b62fa7ce2464783616e34ba Mon Sep 17 00:00:00 2001
From: Gregory Szorc <gps@mozilla.com>
Date: Wed, 29 Aug 2012 14:43:40 -0700
Subject: [PATCH] Bug 785225 - Part 1: Don't rely on Engines singleton in
 AddonsReconciler; r=rnewman

---
 services/sync/modules/addonsreconciler.js | 6 +-----
 services/sync/modules/engines/addons.js   | 9 +++++++++
 2 files changed, 10 insertions(+), 5 deletions(-)

diff --git a/services/sync/modules/addonsreconciler.js b/services/sync/modules/addonsreconciler.js
index 0b2a6b5c7658..f222540db092 100644
--- a/services/sync/modules/addonsreconciler.js
+++ b/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;
     }
 
diff --git a/services/sync/modules/engines/addons.js b/services/sync/modules/engines/addons.js
index 0e80e3fffffa..976f2815527d 100644
--- a/services/sync/modules/engines/addons.js
+++ b/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;
     }
   }