Remove use of index in wallpaper picker code and some refactor

ash/desktop_background/desktop_background_view.h

 // 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.
 
 #ifndef ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_VIEW_H_
 #define ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_VIEW_H_
 
-#include "ash/desktop_background/desktop_background_resources.h"
 #include "ui/gfx/image/image_skia.h"
 #include "ui/views/context_menu_controller.h"
 #include "ui/views/view.h"
 #include "ui/views/widget/widget_delegate.h"
 
 namespace ash {
 namespace internal {
 
 class DesktopBackgroundView : public views::WidgetDelegateView,
                               public views::ContextMenuController {
@@ skipping 10 matching lines @@
   virtual void ShowContextMenuForView(views::View* source,
                                       const gfx::Point& point) OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(DesktopBackgroundView);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_DESKTOP_BACKGROUND_DESKTOP_BACKGROUND_VIEW_H_