Bug 1351964 - Use UI thread for "Tabs:TabsOpened" event; r=sebastian

Use the UI thread for handling "Tabs:TabsOpened", so we don't race with
other tab events that are already handled on the UI thread.

mobile/android/base/java/org/mozilla/gecko/GeckoApp.java

@@ -1780,11 +1780,11 @@ public abstract class GeckoApp
             public void run() {
                 if (TabQueueHelper.TAB_QUEUE_ENABLED && TabQueueHelper.shouldOpenTabQueueUrls(GeckoApp.this)) {
 
-                    getAppEventDispatcher().registerGeckoThreadListener(new BundleEventListener() {
+                    getAppEventDispatcher().registerUiThreadListener(new BundleEventListener() {
                         @Override
                         public void handleMessage(String event, GeckoBundle message, EventCallback callback) {
                             if ("Tabs:TabsOpened".equals(event)) {
-                                getAppEventDispatcher().unregisterGeckoThreadListener(this, "Tabs:TabsOpened");
+                                getAppEventDispatcher().unregisterUiThreadListener(this, "Tabs:TabsOpened");
                                 openTabsRunnable.run();
                             }
                         }