Bug 936008 - Unregister tabs listener in LayerView. r=kats

mobile/android/base/gfx/LayerView.java

@@ -209,6 +209,7 @@ public class LayerView extends FrameLayout implements Tabs.OnTabsChangedListener
         if (mRenderer != null) {
             mRenderer.destroy();
         }
+        Tabs.unregisterOnTabsChangedListener(this);
     }
 
     public void addTouchInterceptor(final TouchEventInterceptor aTouchInterceptor) {