Remove ImageSkia::empty and ImageSkia::extractSubset

ash/desktop_background/desktop_background_view.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/desktop_background/desktop_background_view.h"
 
 #include <limits>
 
 #include "ash/ash_export.h"
 #include "ash/desktop_background/desktop_background_controller.h"
@@ skipping 135 matching lines @@
 
 views::Widget* CreateDesktopBackground(aura::RootWindow* root_window,
                                        int container_id) {
   DesktopBackgroundController* controller = ash::Shell::GetInstance()->
       desktop_background_controller();
   views::Widget* desktop_widget = new views::Widget;
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
   DesktopBackgroundView* view = new DesktopBackgroundView();
   params.delegate = view;
-  if (controller->GetWallpaper().empty())
+  if (controller->GetWallpaper().isNull())
     params.transparent = true;
   params.parent = root_window->GetChildById(container_id);
   desktop_widget->Init(params);
   desktop_widget->SetContentsView(view);
   ash::WindowVisibilityAnimationType animation_type =
       ash::Shell::GetInstance()->user_wallpaper_delegate()->GetAnimationType();
   ash::SetWindowVisibilityAnimationType(desktop_widget->GetNativeView(),
                                         animation_type);
   // Disable animation when creating the first widget. Otherwise, wallpaper
   // will animate from a white screen. Note that boot animation is different.
@@ skipping 13 matching lines @@
   settings.AddObserver(new ShowWallpaperAnimationObserver(root_window,
                                                           container_id,
                                                           desktop_widget));
   desktop_widget->Show();
   desktop_widget->GetNativeView()->SetName("DesktopBackgroundView");
   return desktop_widget;
 }
 
 }  // namespace internal
 }  // namespace ash