--- a/dom/apps/ImportExport.jsm
+++ b/dom/apps/ImportExport.jsm
@@ -8,16 +8,17 @@ const Cu = Components.utils;
 const Cc = Components.classes;
 const Ci = Components.interfaces;
 
 Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/AppsUtils.jsm");
 Cu.import("resource://gre/modules/Promise.jsm");
 Cu.import("resource://gre/modules/Webapps.jsm");
+Cu.import("resource://gre/modules/MessageBroadcaster.jsm");
 
 Cu.importGlobalProperties(['File']);
 
 XPCOMUtils.defineLazyModuleGetter(this, "FileUtils",
   "resource://gre/modules/FileUtils.jsm");
 
 XPCOMUtils.defineLazyModuleGetter(this, "NetUtil",
   "resource://gre/modules/NetUtil.jsm");
@@ -470,20 +471,20 @@ this.ImportExport = {
                                                meta);
 
       // Save the app registry, and sends the various notifications.
       // TODO: stop accessing internal methods of other objects.
       yield DOMApplicationRegistry._saveApps();
 
       app = AppsUtils.cloneAppObject(meta);
       app.manifest = manifest;
-      DOMApplicationRegistry.broadcastMessage("Webapps:AddApp",
-                                              { id: meta.id, app: app });
-      DOMApplicationRegistry.broadcastMessage("Webapps:Install:Return:OK",
-                                              { app: app });
+      MessageBroadcaster.broadcastMessage("Webapps:AddApp",
+                                          { id: meta.id, app: app });
+      MessageBroadcaster.broadcastMessage("Webapps:Install:Return:OK",
+                                          { app: app });
       Services.obs.notifyObservers(null, "webapps-installed",
         JSON.stringify({ manifestURL: meta.manifestURL }));
 
     } catch(e) {
       debug("Import failed: " + e);
       if (appDir && appDir.exists()) {
         appDir.remove(true);
       }

new file mode 100644
--- /dev/null
+++ b/dom/apps/MessageBroadcaster.jsm
@@ -0,0 +1,132 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+// Manages registration of message managers from child processes and
+// broadcasting messages to them.
+
+this.EXPORTED_SYMBOLS = ["MessageBroadcaster"];
+
+this.MessageBroadcaster = {
+  appGetter: null,
+  children: [],
+
+  init: function(aAppGetter) {
+    if (!aAppGetter || typeof aAppGetter !== "function") {
+      throw "MessageBroadcaster.init needs a function parameter";
+    }
+    this.appGetter = aAppGetter;
+  },
+
+  // We manage refcounting of listeners per message manager.
+  addMessageListener: function(aMsgNames, aApp, aMm) {
+    aMsgNames.forEach(aMsgName => {
+      let manifestURL = aApp && aApp.manifestURL;
+      if (!(aMsgName in this.children)) {
+        this.children[aMsgName] = [];
+      }
+
+      let mmFound = this.children[aMsgName].some(mmRef => {
+        if (mmRef.mm === aMm) {
+          mmRef.refCount++;
+          return true;
+        }
+        return false;
+      });
+
+      if (!mmFound) {
+        this.children[aMsgName].push({
+          mm: aMm,
+          refCount: 1
+        });
+      }
+
+      // If the state reported by the registration is outdated, update it now.
+      if (manifestURL && ((aMsgName === 'Webapps:FireEvent') ||
+          (aMsgName === 'Webapps:UpdateState'))) {
+        let app = this.appGetter(aApp.manifestURL);
+        if (app && ((aApp.installState !== app.installState) ||
+                    (aApp.downloading !== app.downloading))) {
+          debug("Got a registration from an outdated app: " +
+                manifestURL);
+          let aEvent ={
+            type: app.installState,
+            app: app,
+            manifestURL: app.manifestURL,
+            manifest: app.manifest
+          };
+          aMm.sendAsyncMessage(aMsgName, aEvent);
+        }
+      }
+    });
+  },
+
+  removeMessageListener: function(aMsgNames, aMm) {
+    if (aMsgNames.length === 1 &&
+        aMsgNames[0] === "Webapps:Internal:AllMessages") {
+      for (let msgName in this.children) {
+        let msg = this.children[msgName];
+
+        for (let mmI = msg.length - 1; mmI >= 0; mmI -= 1) {
+          let mmRef = msg[mmI];
+          if (mmRef.mm === aMm) {
+            msg.splice(mmI, 1);
+          }
+        }
+
+        if (msg.length === 0) {
+          delete this.children[msgName];
+        }
+      }
+      return;
+    }
+
+    aMsgNames.forEach(aMsgName => {
+      if (!(aMsgName in this.children)) {
+        return;
+      }
+
+      let removeIndex;
+      this.children[aMsgName].some((mmRef, index) => {
+        if (mmRef.mm === aMm) {
+          mmRef.refCount--;
+          if (mmRef.refCount === 0) {
+            removeIndex = index;
+          }
+          return true;
+        }
+        return false;
+      });
+
+      if (removeIndex) {
+        this.children[aMsgName].splice(removeIndex, 1);
+      }
+    });
+  },
+
+  // Some messages can be listened by several content processes:
+  // Webapps:AddApp
+  // Webapps:RemoveApp
+  // Webapps:Install:Return:OK
+  // Webapps:Uninstall:Return:OK
+  // Webapps:Uninstall:Broadcast:Return:OK
+  // Webapps:FireEvent
+  // Webapps:checkForUpdate:Return:OK
+  // Webapps:UpdateState
+  broadcastMessage: function(aMsgName, aContent) {
+    if (!(aMsgName in this.children)) {
+      return;
+    }
+    this.children[aMsgName].forEach((mmRef) => {
+      mmRef.mm.sendAsyncMessage(aMsgName, this.formatMessage(aContent));
+    });
+  },
+
+  formatMessage: function(aData) {
+    let msg = aData;
+    delete msg["mm"];
+    return msg;
+  },
+}

--- a/dom/apps/Webapps.jsm
+++ b/dom/apps/Webapps.jsm
@@ -37,16 +37,17 @@ Cu.import("resource://gre/modules/XPCOMU
 Cu.import("resource://gre/modules/Services.jsm");
 Cu.import("resource://gre/modules/FileUtils.jsm");
 Cu.import('resource://gre/modules/ActivitiesService.jsm');
 Cu.import("resource://gre/modules/AppsUtils.jsm");
 Cu.import("resource://gre/modules/AppDownloadManager.jsm");
 Cu.import("resource://gre/modules/osfile.jsm");
 Cu.import("resource://gre/modules/Task.jsm");
 Cu.import("resource://gre/modules/Promise.jsm");
+Cu.import("resource://gre/modules/MessageBroadcaster.jsm");
 
 XPCOMUtils.defineLazyGetter(this, "UserCustomizations", function() {
   let enabled = false;
   try {
     enabled = Services.prefs.getBoolPref("dom.apps.customization.enabled");
   } catch(e) {}
 
   if (enabled) {
@@ -190,17 +191,16 @@ this.DOMApplicationRegistry = {
   get kPackaged()       "packaged",
   get kHosted()         "hosted",
   get kHostedAppcache() "hosted-appcache",
   get kTrustedHosted()  "hosted-trusted",
 
   // Path to the webapps.json file where we store the registry data.
   appsFile: null,
   webapps: { },
-  children: [ ],
   allAppsLaunchable: false,
   _updateHandlers: [ ],
   _pendingUninstalls: {},
   _contentActions: new Map(),
   dirKey: DIRECTORY_NAME,
 
   init: function() {
     // Keep the messages in sync with the lazy-loading in browser.js (bug 1171013).
@@ -246,19 +246,21 @@ this.DOMApplicationRegistry = {
 
     AppDownloadManager.registerCancelFunction(this.cancelDownload.bind(this));
 
     this.appsFile = FileUtils.getFile(DIRECTORY_NAME,
                                       ["webapps", "webapps.json"], true).path;
 
     this.loadAndUpdateApps();
 
-    Langpacks.registerRegistryFunctions(this.broadcastMessage.bind(this),
+    Langpacks.registerRegistryFunctions(MessageBroadcaster.broadcastMessage.bind(MessageBroadcaster),
                                         this._appIdForManifestURL.bind(this),
                                         this.getFullAppByManifestURL.bind(this));
+
+    MessageBroadcaster.init(this.getAppByManifestURL);
   },
 
   // loads the current registry, that could be empty on first run.
   loadCurrentRegistry: function() {
     return AppsUtils.loadJSONAsync(this.appsFile).then((aData) => {
       if (!aData) {
         return;
       }
@@ -1175,103 +1177,16 @@ this.DOMApplicationRegistry = {
       cpmm = null;
       ppmm = null;
     } else if (aTopic == "memory-pressure") {
       // Clear the manifest cache on memory pressure.
       this._manifestCache = {};
     }
   },
 
-  addMessageListener: function(aMsgNames, aApp, aMm) {
-    aMsgNames.forEach(function (aMsgName) {
-      let man = aApp && aApp.manifestURL;
-      if (!(aMsgName in this.children)) {
-        this.children[aMsgName] = [];
-      }
-
-      let mmFound = this.children[aMsgName].some(function(mmRef) {
-        if (mmRef.mm === aMm) {
-          mmRef.refCount++;
-          return true;
-        }
-        return false;
-      });
-
-      if (!mmFound) {
-        this.children[aMsgName].push({
-          mm: aMm,
-          refCount: 1
-        });
-      }
-
-      // If the state reported by the registration is outdated, update it now.
-      if ((aMsgName === 'Webapps:FireEvent') ||
-          (aMsgName === 'Webapps:UpdateState')) {
-        if (man) {
-          let app = this.getAppByManifestURL(aApp.manifestURL);
-          if (app && ((aApp.installState !== app.installState) ||
-                      (aApp.downloading !== app.downloading))) {
-            debug("Got a registration from an outdated app: " +
-                  aApp.manifestURL);
-            let aEvent ={
-              type: app.installState,
-              app: app,
-              manifestURL: app.manifestURL,
-              manifest: app.manifest
-            };
-            aMm.sendAsyncMessage(aMsgName, aEvent);
-          }
-        }
-      }
-    }, this);
-  },
-
-  removeMessageListener: function(aMsgNames, aMm) {
-    if (aMsgNames.length === 1 &&
-        aMsgNames[0] === "Webapps:Internal:AllMessages") {
-      for (let msgName in this.children) {
-        let msg = this.children[msgName];
-
-        for (let mmI = msg.length - 1; mmI >= 0; mmI -= 1) {
-          let mmRef = msg[mmI];
-          if (mmRef.mm === aMm) {
-            msg.splice(mmI, 1);
-          }
-        }
-
-        if (msg.length === 0) {
-          delete this.children[msgName];
-        }
-      }
-      return;
-    }
-
-    aMsgNames.forEach(function(aMsgName) {
-      if (!(aMsgName in this.children)) {
-        return;
-      }
-
-      let removeIndex;
-      this.children[aMsgName].some(function(mmRef, index) {
-        if (mmRef.mm === aMm) {
-          mmRef.refCount--;
-          if (mmRef.refCount === 0) {
-            removeIndex = index;
-          }
-          return true;
-        }
-        return false;
-      });
-
-      if (removeIndex) {
-        this.children[aMsgName].splice(removeIndex, 1);
-      }
-    }, this);
-  },
-
   formatMessage: function(aData) {
     let msg = aData;
     delete msg["mm"];
     return msg;
   },
 
   receiveMessage: function(aMessage) {
     // nsIPrefBranch throws if pref does not exist, faster to simply write
@@ -1344,23 +1259,23 @@ this.DOMApplicationRegistry = {
         this.notifyAppsRegistryReady();
         break;
       case "Webapps:GetList":
         // GetList is special because it's synchronous. So far so well, it's the
         // only synchronous message, if we get more at some point they should get
         // this treatment also.
         return this.doGetList();
       case "child-process-shutdown":
-        this.removeMessageListener(["Webapps:Internal:AllMessages"], mm);
+        MessageBroadcaster.removeMessageListener(["Webapps:Internal:AllMessages"], mm);
         break;
       case "Webapps:RegisterForMessages":
-        this.addMessageListener(msg.messages, msg.app, mm);
+        MessageBroadcaster.addMessageListener(msg.messages, msg.app, mm);
         break;
       case "Webapps:UnregisterForMessages":
-        this.removeMessageListener(msg, mm);
+        MessageBroadcaster.removeMessageListener(msg, mm);
         break;
       default:
         processedImmediately = false;
     }
 
     if (processedImmediately) {
       return;
     }
@@ -1455,34 +1370,16 @@ this.DOMApplicationRegistry = {
       }
     });
   },
 
   getAppInfo: function getAppInfo(aAppId) {
     return AppsUtils.getAppInfo(this.webapps, aAppId);
   },
 
-  // Some messages can be listened by several content processes:
-  // Webapps:AddApp
-  // Webapps:RemoveApp
-  // Webapps:Install:Return:OK
-  // Webapps:Uninstall:Return:OK
-  // Webapps:Uninstall:Broadcast:Return:OK
-  // Webapps:FireEvent
-  // Webapps:checkForUpdate:Return:OK
-  // Webapps:UpdateState
-  broadcastMessage: function broadcastMessage(aMsgName, aContent) {
-    if (!(aMsgName in this.children)) {
-      return;
-    }
-    this.children[aMsgName].forEach((mmRef) => {
-      mmRef.mm.sendAsyncMessage(aMsgName, this.formatMessage(aContent));
-    });
-  },
-
   registerUpdateHandler: function(aHandler) {
     this._updateHandlers.push(aHandler);
   },
 
   unregisterUpdateHandler: function(aHandler) {
     let index = this._updateHandlers.indexOf(aHandler);
     if (index != -1) {
       this._updateHandlers.splice(index, 1);
@@ -1749,26 +1646,26 @@ this.DOMApplicationRegistry = {
 
     // Ensure we don't send additional errors for this download
     app.isCanceling = true;
 
     // Ensure this app can be downloaded again after canceling
     app.downloading = false;
 
     this._saveApps().then(() => {
-      this.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         app: {
           progress: 0,
           installState: download.previousState,
           downloading: false
         },
         error: error,
         id: app.id
       })
-      this.broadcastMessage("Webapps:FireEvent", {
+      MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
         eventType: "downloaderror",
         manifestURL: app.manifestURL
       });
     });
     AppDownloadManager.remove(aManifestURL);
   },
 
   startDownload: Task.async(function*(aManifestURL) {
@@ -1785,21 +1682,21 @@ this.DOMApplicationRegistry = {
     if (app.downloading) {
       debug("app is already downloading. Ignoring.");
       throw new Error("APP_IS_DOWNLOADING");
     }
 
     // If the caller is trying to start a download but we have nothing to
     // download, send an error.
     if (!app.downloadAvailable) {
-      this.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         error: "NO_DOWNLOAD_AVAILABLE",
         id: app.id
       });
-      this.broadcastMessage("Webapps:FireEvent", {
+      MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
         eventType: "downloaderror",
         manifestURL: app.manifestURL
       });
       throw new Error("NO_DOWNLOAD_AVAILABLE");
     }
 
     // First of all, we check if the download is supposed to update an
     // already installed application.
@@ -1833,22 +1730,22 @@ this.DOMApplicationRegistry = {
       } else {
         // Hosted app with no appcache, nothing to do, but we fire a
         // downloaded event.
         debug("No appcache found, sending 'downloaded' for " + aManifestURL);
         app.downloadAvailable = false;
 
         yield this._saveApps();
 
-        this.broadcastMessage("Webapps:UpdateState", {
+        MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
           app: app,
           manifest: jsonManifest,
           id: app.id
         });
-        this.broadcastMessage("Webapps:FireEvent", {
+        MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
           eventType: "downloadsuccess",
           manifestURL: aManifestURL
         });
       }
 
       return;
     }
 
@@ -1886,21 +1783,21 @@ this.DOMApplicationRegistry = {
     app = this.webapps[id];
 
     // Set state and fire events.
     app.downloading = false;
     app.downloadAvailable = false;
     app.readyToApplyDownload = true;
     app.updateTime = Date.now();
 
-    this.broadcastMessage("Webapps:UpdateState", {
+    MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
       app: app,
       id: app.id
     });
-    this.broadcastMessage("Webapps:FireEvent", {
+    MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
       eventType: "downloadsuccess",
       manifestURL: aManifestURL
     });
     if (app.installState == "pending") {
       // We restarted a failed download, apply it automatically.
       this.applyDownload(aManifestURL);
     }
   }),
@@ -2007,22 +1904,22 @@ this.DOMApplicationRegistry = {
         { manifest: newManifest,
           origin: app.origin,
           manifestURL: app.manifestURL,
           kind: app.kind },
         true);
     }
     this.updateDataStore(this.webapps[id].localId, app.origin,
                          app.manifestURL, newManifest);
-    this.broadcastMessage("Webapps:UpdateState", {
+    MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
       app: app,
       manifest: newManifest,
       id: app.id
     });
-    this.broadcastMessage("Webapps:FireEvent", {
+    MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
       eventType: "downloadapplied",
       manifestURL: app.manifestURL
     });
   }),
 
   startOfflineCacheDownload: function(aManifest, aApp, aProfileDir, aIsUpdate) {
     debug("startOfflineCacheDownload " + aApp.id + " " + aApp.kind);
     if ((aApp.kind !== this.kHostedAppcache &&
@@ -2045,17 +1942,17 @@ this.DOMApplicationRegistry = {
       aApp.installState = "updating";
     }
 
     // We set the 'downloading' flag and update the apps registry right before
     // starting the app download/update.
     aApp.downloading = true;
     aApp.progress = 0;
     DOMApplicationRegistry._saveApps().then(() => {
-      DOMApplicationRegistry.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         // Clear any previous errors.
         error: null,
         app: {
           downloading: true,
           installState: aApp.installState,
           progress: 0
         },
         id: aApp.id
@@ -2186,21 +2083,21 @@ this.DOMApplicationRegistry = {
         // "downloadapplied".
         let updateObserver = {
           observe: function(aSubject, aTopic, aObsData) {
             debug("onlyCheckAppCache updateSvc.checkForUpdate return for " +
                   app.manifestURL + " - event is " + aTopic);
             if (aTopic == "offline-cache-update-available") {
               app.downloadAvailable = true;
               this._saveApps().then(() => {
-                this.broadcastMessage("Webapps:UpdateState", {
+                MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
                   app: app,
                   id: app.id
                 });
-                this.broadcastMessage("Webapps:FireEvent", {
+                MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
                   eventType: "downloadavailable",
                   manifestURL: app.manifestURL,
                   requestID: aData.requestID
                 });
               });
             } else {
               sendError("NOT_UPDATABLE");
             }
@@ -2386,21 +2283,21 @@ this.DOMApplicationRegistry = {
     // event.
     aApp.downloadAvailable = true;
     aApp.downloadSize = manifest.size;
     aApp.updateManifest = aNewManifest;
     this._saveWidgetsFullPath(manifest, aApp);
 
     yield this._saveApps();
 
-    this.broadcastMessage("Webapps:UpdateState", {
+    MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
       app: aApp,
       id: aApp.id
     });
-    this.broadcastMessage("Webapps:FireEvent", {
+    MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
       eventType: "downloadavailable",
       manifestURL: aApp.manifestURL,
       requestID: aData.requestID
     });
   }),
 
   // A hosted app is updated if the app manifest or the appcache needs
   // updating. Even if the app manifest has not changed, we still check
@@ -2418,22 +2315,22 @@ this.DOMApplicationRegistry = {
 
     aApp.manifest = aNewManifest || aOldManifest;
 
     let manifest =
       new ManifestHelper(aApp.manifest, aApp.origin, aApp.manifestURL);
     aApp.role = manifest.role || "";
 
     if (!AppsUtils.checkAppRole(aApp.role, aApp.appStatus)) {
-      this.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         app: aApp,
         manifest: aApp.manifest,
         id: aApp.id
       });
-      this.broadcastMessage("Webapps:FireEvent", {
+      MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
         eventType: "downloadapplied",
         manifestURL: aApp.manifestURL,
         requestID: aData.requestID
       });
       delete aApp.manifest;
       return;
     }
 
@@ -2469,22 +2366,22 @@ this.DOMApplicationRegistry = {
 
     // Update the registry.
     this.webapps[aId] = aApp;
     yield this._saveApps();
 
     if ((aApp.kind !== this.kHostedAppcache &&
          aApp.kind !== this.kTrustedHosted) ||
          !aApp.manifest.appcache_path) {
-      this.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         app: aApp,
         manifest: aApp.manifest,
         id: aApp.id
       });
-      this.broadcastMessage("Webapps:FireEvent", {
+      MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
         eventType: "downloadapplied",
         manifestURL: aApp.manifestURL,
         requestID: aData.requestID
       });
     } else {
       // Check if the appcache is updatable, and send "downloadavailable" or
       // "downloadapplied".
       debug("updateHostedApp: updateSvc.checkForUpdate for " +
@@ -2503,22 +2400,22 @@ this.DOMApplicationRegistry = {
 
       let eventType =
         topic == "offline-cache-update-available" ? "downloadavailable"
                                                   : "downloadapplied";
 
       aApp.downloadAvailable = (eventType == "downloadavailable");
       yield this._saveApps();
 
-      this.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         app: aApp,
         manifest: aApp.manifest,
         id: aApp.id
       });
-      this.broadcastMessage("Webapps:FireEvent", {
+      MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
         eventType: eventType,
         manifestURL: aApp.manifestURL,
         requestID: aData.requestID
       });
     }
 
     delete aApp.manifest;
   }),
@@ -3045,17 +2942,17 @@ this.DOMApplicationRegistry = {
 
     // Store the manifest and the updateManifest.
     this._writeManifestFile(app.id, false, aManifest);
     if (aUpdateManifest) {
       this._writeManifestFile(app.id, true, aUpdateManifest);
     }
 
     this._saveApps().then(() => {
-      this.broadcastMessage("Webapps:AddApp",
+      MessageBroadcaster.broadcastMessage("Webapps:AddApp",
                             { id: app.id, app: app, manifest: aManifest });
     });
   }),
 
   confirmInstall: Task.async(function*(aData, aProfileDir, aInstallSuccessCallback) {
     debug("confirmInstall");
 
     let origin = Services.io.newURI(aData.app.origin, null, null);
@@ -3161,17 +3058,17 @@ this.DOMApplicationRegistry = {
 
     // We notify about the successful installation via mgmt.oninstall and the
     // corresponding DOMRequest.onsuccess event as soon as the app is properly
     // saved in the registry.
     yield this._saveApps();
 
     aData.isPackage ? appObject.updateManifest = jsonManifest :
                       appObject.manifest = jsonManifest;
-    this.broadcastMessage("Webapps:AddApp", { id: id, app: appObject });
+    MessageBroadcaster.broadcastMessage("Webapps:AddApp", { id: id, app: appObject });
 
     if (!aData.isPackage) {
       this.updateAppHandlers(null, app.manifest, app);
       if (aInstallSuccessCallback) {
         try {
           yield aInstallSuccessCallback(app, app.manifest);
         } catch (e) {
           // Ignore exceptions during the local installation of
@@ -3186,17 +3083,17 @@ this.DOMApplicationRegistry = {
       // Skip directly to onInstallSuccessAck, since there isn't
       // a WebappsRegistry to receive Webapps:Install:Return:OK and respond
       // Webapps:Install:Return:Ack when an app is being auto-installed.
       this.onInstallSuccessAck(app.manifestURL);
     } else {
       // Broadcast Webapps:Install:Return:OK so the WebappsRegistry can notify
       // the installing page about the successful install, after which it'll
       // respond Webapps:Install:Return:Ack, which calls onInstallSuccessAck.
-      this.broadcastMessage("Webapps:Install:Return:OK", aData);
+      MessageBroadcaster.broadcastMessage("Webapps:Install:Return:OK", aData);
     }
 
     Services.obs.notifyObservers(null, "webapps-installed",
       JSON.stringify({ manifestURL: app.manifestURL }));
 
     if (aData.forceSuccessAck) {
       // If it's a local install, there's no content process so just
       // ack the install.
@@ -3243,17 +3140,17 @@ this.DOMApplicationRegistry = {
     yield this._saveApps();
 
     this.updateAppHandlers(null, aManifest, aNewApp);
     // Clear the manifest cache in case it holds the update manifest.
     if (aId in this._manifestCache) {
       delete this._manifestCache[aId];
     }
 
-    this.broadcastMessage("Webapps:AddApp",
+    MessageBroadcaster.broadcastMessage("Webapps:AddApp",
                           { id: aId, app: aNewApp, manifest: aManifest });
     Services.obs.notifyObservers(null, "webapps-installed",
       JSON.stringify({ manifestURL: aNewApp.manifestURL }));
 
     if (supportUseCurrentProfile()) {
       // Update the permissions for this app.
       PermissionsInstaller.installPermissions({
         manifest: aManifest,
@@ -3271,29 +3168,29 @@ this.DOMApplicationRegistry = {
         yield aInstallSuccessCallback(aNewApp, aManifest, zipFile.path);
       } catch (e) {
         // Ignore exceptions during the local installation of
         // an app. If it fails, the app will anyway be considered
         // as not installed because isLaunchable will return false.
       }
     }
 
-    this.broadcastMessage("Webapps:UpdateState", {
+    MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
       app: app,
       manifest: aManifest,
       manifestURL: aNewApp.manifestURL
     });
 
     // Check if we have asm.js code to preload for this application.
     yield ScriptPreloader.preload(aNewApp, aManifest);
 
     // Update langpack information.
     yield Langpacks.register(aNewApp, aManifest);
 
-    this.broadcastMessage("Webapps:FireEvent", {
+    MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
       eventType: ["downloadsuccess", "downloadapplied"],
       manifestURL: aNewApp.manifestURL
     });
   }),
 
   _nextLocalId: function() {
     let id = Services.prefs.getIntPref("dom.mozApps.maxLocalId") + 1;
 
@@ -3404,17 +3301,17 @@ this.DOMApplicationRegistry = {
 
     // initialize the progress to 0 right now
     aOldApp.progress = 0;
 
     // Save the current state of the app to handle cases where we may be
     // retrying a past download.
     yield DOMApplicationRegistry._saveApps();
 
-    DOMApplicationRegistry.broadcastMessage("Webapps:UpdateState", {
+    MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         // Clear any previous download errors.
         error: null,
         app: aOldApp,
         id: aId
     });
 
     let zipFile = yield this._getPackage(requestChannel, aId, aOldApp, aNewApp);
 
@@ -3573,23 +3470,23 @@ this.DOMApplicationRegistry = {
         throw Cr.NS_ERROR_NOT_IMPLEMENTED;
       }
     };
 
     return requestChannel;
   },
 
   _sendDownloadProgressEvent: function(aNewApp, aProgress) {
-    this.broadcastMessage("Webapps:UpdateState", {
+    MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
       app: {
         progress: aProgress
       },
       id: aNewApp.id
     });
-    this.broadcastMessage("Webapps:FireEvent", {
+    MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
       eventType: "progress",
       manifestURL: aNewApp.manifestURL
     });
   },
 
   _getPackage: function(aRequestChannel, aId, aOldApp, aNewApp) {
     let deferred = Promise.defer();
 
@@ -3687,21 +3584,21 @@ this.DOMApplicationRegistry = {
         staged.moveTo(staged.parent, "update.webapp");
       } catch (ex) {
         // We don't really mind much if this fails.
       }
     }
 
     // Save the updated registry, and cleanup the tmp directory.
     this._saveApps().then(() => {
-      this.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         app: aApp,
         id: aApp.id
       });
-      this.broadcastMessage("Webapps:FireEvent", {
+      MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
         manifestURL: aApp.manifestURL,
         eventType: ["downloadsuccess", "downloadapplied"]
       });
     });
     let file = FileUtils.getFile("TmpD", ["webapps", aApp.id], false);
     if (file && file.exists()) {
       file.remove(true);
     }
@@ -4035,17 +3932,17 @@ this.DOMApplicationRegistry = {
         delete this.webapps[oldId];
         // Rename the directories where the files are installed.
         [DIRECTORY_NAME, "TmpD"].forEach(function(aDir) {
           let parent = FileUtils.getDir(aDir, ["webapps"], true, true);
           let dir = FileUtils.getDir(aDir, ["webapps", oldId], true, true);
           dir.moveTo(parent, newId);
         });
         // Signals that we need to swap the old id with the new app.
-        this.broadcastMessage("Webapps:UpdateApp", { oldId: oldId,
+        MessageBroadcaster.broadcastMessage("Webapps:UpdateApp", { oldId: oldId,
                                                      newId: newId,
                                                      app: aOldApp });
 
       }
     }
   },
 
   _getIds: function(aIsSigned, aZipReader, aConverter, aNewApp, aOldApp,
@@ -4147,22 +4044,22 @@ this.DOMApplicationRegistry = {
 
     // Erase the .staged properties only if there's no download available
     // anymore.
     if (!aOldApp.downloadAvailable && aOldApp.staged) {
       delete aOldApp.staged;
     }
 
     this._saveApps().then(() => {
-      this.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         app: aOldApp,
         error: aError,
         id: aId
       });
-      this.broadcastMessage("Webapps:FireEvent", {
+      MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
         eventType: "downloaderror",
         manifestURL:  aNewApp.manifestURL
       });
     });
     AppDownloadManager.remove(aNewApp.manifestURL);
   },
 
   doUninstall: Task.async(function*(aData, aMm) {
@@ -4231,18 +4128,18 @@ this.DOMApplicationRegistry = {
     try {
       dir.remove(true);
     } catch (e) {}
 
     delete this.webapps[id];
 
     yield this._saveApps();
 
-    this.broadcastMessage("Webapps:Uninstall:Broadcast:Return:OK", aApp);
-    this.broadcastMessage("Webapps:RemoveApp", { id: id });
+    MessageBroadcaster.broadcastMessage("Webapps:Uninstall:Broadcast:Return:OK", aApp);
+    MessageBroadcaster.broadcastMessage("Webapps:RemoveApp", { id: id });
 
     return aApp;
   }),
 
   _promptForUninstall: function(aData) {
     let deferred = Promise.defer();
     this._pendingUninstalls[aData.requestID] = deferred;
     Services.obs.notifyObservers(null, "webapps-ask-uninstall",
@@ -4652,21 +4549,21 @@ this.DOMApplicationRegistry = {
     if (!id || !this.webapps[id]) {
       return;
     }
 
     debug("Enabling " + id);
     let app = this.webapps[id];
     app.enabled = aData.enabled;
     this._saveApps().then(() => {
-      DOMApplicationRegistry.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         app: app,
         id: app.id
       });
-      this.broadcastMessage("Webapps:SetEnabled:Return", app);
+      MessageBroadcaster.broadcastMessage("Webapps:SetEnabled:Return", app);
     });
 
     // Update customization.
     this.getManifestFor(app.manifestURL).then((aManifest) => {
       app.enabled ? UserCustomizations.register(aManifest, app)
                   : UserCustomizations.unregister(aManifest, app);
     });
   },
@@ -4876,21 +4773,21 @@ let AppcacheObserver = function(aApp) {
   // Send a first progress event to correctly set the DOM object's properties.
   this._sendProgressEvent();
 };
 
 AppcacheObserver.prototype = {
   // nsIOfflineCacheUpdateObserver implementation
   _sendProgressEvent: function() {
     let app = this.app;
-    DOMApplicationRegistry.broadcastMessage("Webapps:UpdateState", {
+    MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
       app: app,
       id: app.id
     });
-    DOMApplicationRegistry.broadcastMessage("Webapps:FireEvent", {
+    MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
       eventType: "progress",
       manifestURL: app.manifestURL
     });
   },
 
   updateStateChanged: function appObs_Update(aUpdate, aState) {
     let mustSave = false;
     let app = this.app;
@@ -4908,21 +4805,21 @@ AppcacheObserver.prototype = {
       if (aStatus != "installed") {
         self._sendProgressEvent();
         return;
       }
 
       app.updateTime = Date.now();
       app.downloading = false;
       app.downloadAvailable = false;
-      DOMApplicationRegistry.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         app: app,
         id: app.id
       });
-      DOMApplicationRegistry.broadcastMessage("Webapps:FireEvent", {
+      MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
         eventType: ["downloadsuccess", "downloadapplied"],
         manifestURL: app.manifestURL
       });
     }
 
     let setError = function appObs_setError(aError) {
       debug("Offlinecache setError to " + aError);
       app.downloading = false;
@@ -4930,22 +4827,22 @@ AppcacheObserver.prototype = {
 
       // If we are canceling the download, we already send a DOWNLOAD_CANCELED
       // error.
       if (app.isCanceling) {
         delete app.isCanceling;
         return;
       }
 
-      DOMApplicationRegistry.broadcastMessage("Webapps:UpdateState", {
+      MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
         app: app,
         error: aError,
         id: app.id
       });
-      DOMApplicationRegistry.broadcastMessage("Webapps:FireEvent", {
+      MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
         eventType: "downloaderror",
         manifestURL: app.manifestURL
       });
     }
 
     switch (aState) {
       case Ci.nsIOfflineCacheUpdateObserver.STATE_ERROR:
         aUpdate.removeObserver(this);

--- a/dom/apps/moz.build
+++ b/dom/apps/moz.build
@@ -29,16 +29,17 @@ EXTRA_COMPONENTS += [
     'Webapps.manifest',
 ]
 
 EXTRA_JS_MODULES += [
     'AppDownloadManager.jsm',
     'AppsServiceChild.jsm',
     'FreeSpaceWatcher.jsm',
     'Langpacks.jsm',
+    'MessageBroadcaster.jsm',
     'OfflineCacheInstaller.jsm',
     'PermissionsInstaller.jsm',
     'PermissionsTable.jsm',
     'StoreTrustAnchor.jsm',
     'UserCustomizations.jsm',
 ]
 
 EXTRA_PP_JS_MODULES += [

--- a/toolkit/devtools/server/actors/webapps.js
+++ b/toolkit/devtools/server/actors/webapps.js
@@ -207,16 +207,17 @@ PackageUploadBulkActor.prototype.request
 function WebappsActor(aConnection) {
   debug("init");
   // Load actor dependencies lazily as this actor require extra environnement
   // preparation to work (like have a profile setup in xpcshell tests)
 
   Cu.import("resource://gre/modules/Webapps.jsm");
   Cu.import("resource://gre/modules/AppsUtils.jsm");
   Cu.import("resource://gre/modules/FileUtils.jsm");
+  Cu.import("resource://gre/modules/MessageBroadcaster.jsm");
 
   // Keep reference of already connected app processes.
   // values: app frame message manager
   this._connectedApps = new Set();
 
   this.conn = aConnection;
   this._uploads = [];
   this._actorPool = new ActorPool(this.conn);
@@ -284,27 +285,27 @@ WebappsActor.prototype = {
         if (aApp.kind == undefined) {
           aApp.kind = manifest.appcache_path ? reg.kHostedAppcache
                                              : reg.kHosted;
         }
 
         // Needed to evict manifest cache on content side
         // (has to be dispatched first, otherwise other messages like
         // Install:Return:OK are going to use old manifest version)
-        reg.broadcastMessage("Webapps:UpdateState", {
+        MessageBroadcaster.broadcastMessage("Webapps:UpdateState", {
           app: aApp,
           manifest: manifest,
           id: aApp.id
         });
-        reg.broadcastMessage("Webapps:FireEvent", {
+        MessageBroadcaster.broadcastMessage("Webapps:FireEvent", {
           eventType: ["downloadsuccess", "downloadapplied"],
           manifestURL: aApp.manifestURL
         });
-        reg.broadcastMessage("Webapps:AddApp", { id: aId, app: aApp });
-        reg.broadcastMessage("Webapps:Install:Return:OK", {
+        MessageBroadcaster.broadcastMessage("Webapps:AddApp", { id: aId, app: aApp });
+        MessageBroadcaster.broadcastMessage("Webapps:Install:Return:OK", {
           app: aApp,
           oid: "foo",
           requestID: "bar"
         });
 
         Services.obs.notifyObservers(null, "webapps-installed",
           JSON.stringify({ manifestURL: aApp.manifestURL }));