Fix doubling of channel listing

Test: toggle a notification group on/off
Change-Id: Ia93cf8084aee0c886a591301cba764975e5e0147
Fixes: 124384280

src/com/android/settings/notification/AppNotificationSettings.java

@@ -255,7 +255,7 @@ public class AppNotificationSettings extends NotificationSettingsBase {
                 int childCount = groupGroup.getPreferenceCount();
                 for (int i = 0; i < childCount; i++) {
                     Preference pref = groupGroup.getPreference(i);
-                    if (pref instanceof MasterCheckBoxPreference) {
+                    if (pref instanceof ChannelSummaryPreference) {
                         toRemove.add(pref);
                     }
                 }

src/com/android/settings/notification/NotificationSettingsBase.java

@@ -309,7 +309,9 @@ abstract public class NotificationSettingsBase extends DashboardFragment {
                         return true;
                     }
                 });
+        if (parent.findPreference(channelPref.getKey()) == null) {
             parent.addPreference(channelPref);
+        }
         return channelPref;
     }