Fix crash when launching zen mode settings.

The switch bar is only accessible in onActivityCreated.  Defer
initialization until then.

Bug:15214851
Change-Id: Ie026d46250dae397ba0af02e833bb178631fe708

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

@@ -141,8 +141,8 @@ public class ZenModeSettings extends SettingsPreferenceFragment implements Index
     }
 
     @Override
-    public void onCreate(Bundle icicle) {
-        super.onCreate(icicle);
+    public void onActivityCreated(Bundle savedInstanceState) {
+        super.onActivityCreated(savedInstanceState);
         mContext = getActivity();
         mPM = mContext.getPackageManager();
         final Resources res = mContext.getResources();