MessageReceiver is an event target

Rather than asking for a global target, the message receiver implements
the EventTarget interface itself. It does not expose the dispatchEvent
method, however. This ensures that events can only be triggered from
within the internal MessageReceiver class, which means we no longer need
to namespace them.

// FREEBIE

js/background.js

@@ -49,29 +49,33 @@
             }
         };
 
-        window.addEventListener('textsecure:message', onMessageReceived);
-        window.addEventListener('textsecure:receipt', onDeliveryReceipt);
-        window.addEventListener('textsecure:contact', onContactReceived);
-        window.addEventListener('textsecure:group', onGroupReceived);
-        window.addEventListener('textsecure:sent', onSentMessage);
-        window.addEventListener('textsecure:error', onError);
-
         if (open) {
             openInbox();
         }
-
         function init() {
             window.removeEventListener('online', init);
             if (!textsecure.registration.isDone()) { return; }
 
-            // initialize the socket and start listening for messages
-            messageReceiver = new textsecure.MessageReceiver(
-                'https://textsecure-service-staging.whispersystems.org',
-                textsecure.storage.get('number_id'),
-                textsecure.storage.get('password'),
-                textsecure.storage.get('signaling_key'),
-                window
-            );
+            if (messageReceiver) { messageReceiver.close(); }
+
+            var URL = 'https://textsecure-service-staging.whispersystems.org';
+            var USERNAME = storage.get('number_id');
+            var PASSWORD = storage.get('password');
+            var mySignalingKey = storage.get('signaling_key');
+
+            messageReceiver = new textsecure.MessageReceiver(URL, USERNAME, PASSWORD, mySignalingKey);
+            messageReceiver.addEventListener('message', onMessageReceived);
+            messageReceiver.addEventListener('receipt', onDeliveryReceipt);
+            messageReceiver.addEventListener('contact', onContactReceived);
+            messageReceiver.addEventListener('group', onGroupReceived);
+            messageReceiver.addEventListener('sent', onSentMessage);
+            messageReceiver.addEventListener('error', onError);
+
+            messageReceiver.addEventListener('contactsync', onContactSyncComplete);
+        }
+
+        function onContactSyncComplete() {
+            window.dispatchEvent(new Event('textsecure:contactsync'));
         }
 
         function onContactReceived(ev) {