messageTray: Add an indicatorCount property to the tray

So we don't have to do the property tracking here...

js/ui/messageTray.js

@@ -1821,7 +1821,8 @@ const MessageTray = new Lang.Class({
             summaryItem: new SummaryItem(source),
             notifyId: 0,
             destroyId: 0,
-            mutedChangedId: 0
+            mutedChangedId: 0,
+            countChangedId: 0,
         };
         let summaryItem = obj.summaryItem;
 
@@ -1846,6 +1847,9 @@ const MessageTray = new Lang.Class({
                         return source != notification.source;
                     });
             }));
+        obj.countChangedId = source.connect('count-updated', Lang.bind(this, function() {
+            this.emit('indicator-count-updated');
+        }));
 
         summaryItem.actor.connect('clicked', Lang.bind(this,
             function(actor, button) {
@@ -1865,6 +1869,7 @@ const MessageTray = new Lang.Class({
         Meta.later_add(Meta.LaterType.BEFORE_REDRAW, Lang.bind(this, function() { this._updateState(); return false; }));
 
         this.emit('source-added', source);
+        this.emit('indicator-count-updated');
 
         this._updateNoMessagesLabel();
     },
@@ -1883,10 +1888,12 @@ const MessageTray = new Lang.Class({
         source.disconnect(obj.notifyId);
         source.disconnect(obj.destroyId);
         source.disconnect(obj.mutedChangedId);
+        source.disconnect(obj.countChangedId);
 
         summaryItem.destroy();
 
         this.emit('source-removed', source);
+        this.emit('indicator-count-updated');
 
         this._updateNoMessagesLabel();
     },
@@ -1911,6 +1918,23 @@ const MessageTray = new Lang.Class({
         this._removeSource(source);
     },
 
+    get hasChatSources() {
+        for (let source of this._sources.keys())
+            if (source.isChat)
+                return true;
+        return false;
+    },
+
+    get indicatorCount() {
+        if (!this._sources.size)
+            return 0;
+
+        let count = 0;
+        for (let source of this._sources.keys())
+            count += source.indicatorCount;
+        return count;
+    },
+
     _onNotificationDestroy: function(notification) {
         if (this._notification == notification && (this._notificationState == State.SHOWN || this._notificationState == State.SHOWING)) {
             this._updateNotificationTimeout(0);

js/ui/overviewControls.js

@@ -451,45 +451,21 @@ const MessagesIndicator = new Lang.Class({
         this.actor.add_actor(this._container);
         this.actor.add_actor(this._highlight);
 
-        Main.messageTray.connect('source-added', Lang.bind(this, this._onSourceAdded));
+        Main.messageTray.connect('indicator-count-updated', Lang.bind(this, this._sync));
-        Main.messageTray.connect('source-removed', Lang.bind(this, this._onSourceRemoved));
+        this._sync();
-
-        let sources = Main.messageTray.getSources();
-        sources.forEach(Lang.bind(this, function(source) { this._onSourceAdded(null, source); }));
 
         this._viewSelector.connect('page-changed', Lang.bind(this, this._updateVisibility));
         Main.overview.connect('showing', Lang.bind(this, this._updateVisibility));
     },
 
-    _onSourceAdded: function(tray, source) {
+    _sync: function() {
-        if (source.trayIcon)
+        let count = Main.messageTray.indicatorCount;
-            return;
-
-        source.connect('count-updated', Lang.bind(this, this._updateCount));
-        this._sources.push(source);
-        this._updateCount();
-    },
-
-    _onSourceRemoved: function(tray, source) {
-        this._sources.splice(this._sources.indexOf(source), 1);
-        this._updateCount();
-    },
-
-    _updateCount: function() {
-        let count = 0;
-        let hasChats = false;
-        this._sources.forEach(Lang.bind(this,
-            function(source) {
-                count += source.indicatorCount;
-                hasChats |= source.isChat;
-            }));
-
         this._count = count;
         this._label.text = ngettext("%d new message",
                                     "%d new messages",
                                    count).format(count);
 
-        this._icon.visible = hasChats;
+        this._icon.visible = Main.messageTray.hasChatSources;
         this._updateVisibility();
     },