mash: Partially migrate ash/desktop_background to ash common types.

ash/shell.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/shell.h"
 
 #include <algorithm>
 #include <string>
 #include <utility>
 
@@ skipping 39 matching lines @@
 #include "ash/frame/custom_frame_view_ash.h"
 #include "ash/high_contrast/high_contrast_controller.h"
 #include "ash/host/ash_window_tree_host_init_params.h"
 #include "ash/ime/input_method_event_handler.h"
 #include "ash/magnifier/magnification_controller.h"
 #include "ash/magnifier/partial_magnification_controller.h"
 #include "ash/root_window_controller.h"
 #include "ash/shelf/shelf.h"
 #include "ash/shelf/shelf_widget.h"
 #include "ash/shelf/shelf_window_watcher.h"
-#include "ash/shell_factory.h"
 #include "ash/shell_init_params.h"
 #include "ash/utility/screenshot_controller.h"
 #include "ash/wm/ash_focus_rules.h"
 #include "ash/wm/ash_native_cursor_manager.h"
 #include "ash/wm/event_client_impl.h"
 #include "ash/wm/lock_state_controller.h"
 #include "ash/wm/overlay_event_filter.h"
 #include "ash/wm/overview/scoped_overview_animation_settings_factory_aura.h"
 #include "ash/wm/power_button_controller.h"
 #include "ash/wm/resize_shadow_controller.h"
@@ skipping 1017 matching lines @@
 
 void Shell::OnWindowActivated(
     aura::client::ActivationChangeObserver::ActivationReason reason,
     aura::Window* gained_active,
     aura::Window* lost_active) {
   if (gained_active)
     target_root_window_ = gained_active->GetRootWindow();
 }
 
 }  // namespace ash