Revert of Remove header dependencies from sequence_checker.h to sequenced_worker_pool.h

ash/common/wm_shell.cc

 // Copyright 2016 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/common/wm_shell.h"
 
 #include <utility>
 
 #include "ash/common/accelerators/accelerator_controller.h"
 #include "ash/common/accelerators/ash_focus_manager_factory.h"
@@ skipping 36 matching lines @@
 #include "ash/common/wm/system_modal_container_layout_manager.h"
 #include "ash/common/wm/window_cycle_controller.h"
 #include "ash/common/wm_activation_observer.h"
 #include "ash/common/wm_window.h"
 #include "ash/public/cpp/shell_window_ids.h"
 #include "ash/root_window_controller.h"
 #include "ash/shell.h"
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
-#include "base/threading/sequenced_worker_pool.h"
 #include "services/preferences/public/cpp/pref_client_store.h"
 #include "services/preferences/public/interfaces/preferences.mojom.h"
 #include "services/service_manager/public/cpp/connector.h"
 #include "ui/app_list/presenter/app_list.h"
 #include "ui/display/display.h"
 #include "ui/views/focus/focus_manager_factory.h"
 #include "ui/wm/public/activation_client.h"
 
 namespace ash {
 
@@ skipping 388 matching lines @@
 
 void WmShell::OnAttemptToReactivateWindow(aura::Window* request_active,
                                           aura::Window* actual_active) {
   for (auto& observer : activation_observers_) {
     observer.OnAttemptToReactivateWindow(WmWindow::Get(request_active),
                                          WmWindow::Get(actual_active));
   }
 }
 
 }  // namespace ash