Update to follow framework.

Change-Id: I38c6e59234432b103a619dbf5dab0b1fd029f101
diff --git a/src/com/android/wallpaper/livepicker/LiveWallpaperPreview.java b/src/com/android/wallpaper/livepicker/LiveWallpaperPreview.java
index d4f7ef7..55e0d24 100644
--- a/src/com/android/wallpaper/livepicker/LiveWallpaperPreview.java
+++ b/src/com/android/wallpaper/livepicker/LiveWallpaperPreview.java
@@ -306,5 +306,9 @@
         public ParcelFileDescriptor setWallpaper(String name) {
             return null;
         }
+
+        @Override
+        public void engineShown(IWallpaperEngine engine) throws RemoteException {
+        }
     }
 }