Restore to user selected wallpaper after browser crash

ash/test/test_shell_delegate.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "ash/test/test_shell_delegate.h"
 
 #include <algorithm>
 
 #include "ash/screenshot_delegate.h"
 #include "ash/shell.h"
@@ skipping 51 matching lines @@
 LauncherDelegate* TestShellDelegate::CreateLauncherDelegate(
     ash::LauncherModel* model) {
   return NULL;
 }
 
 SystemTrayDelegate* TestShellDelegate::CreateSystemTrayDelegate(
     SystemTray* tray) {
   return NULL;
 }
 
+UserWallpaperDelegate* TestShellDelegate::CreateUserWallpaperDelegate() {
+  return NULL;
+}
+
 }  // namespace test
 }  // namespace ash