chromeos: Remove some WmWindow usage from ash/system

ash/system/user/user_view.cc

 // Copyright 2014 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/system/user/user_view.h"
 
 #include <algorithm>
 #include <utility>
 
 #include "ash/multi_profile_uma.h"
@@ skipping 306 matching lines @@
   // item since it will destroyed automatically before the menu / user menu item
   // gets destroyed..
   user_dropdown_widget_.reset(new views::Widget);
   views::Widget::InitParams params;
   params.type = views::Widget::InitParams::TYPE_MENU;
   params.keep_on_top = true;
   params.accept_events = true;
   params.ownership = views::Widget::InitParams::WIDGET_OWNS_NATIVE_WIDGET;
   params.opacity = views::Widget::InitParams::TRANSLUCENT_WINDOW;
   params.name = "AddUserMenuOption";
-  WmWindow::Get(GetWidget()->GetNativeWindow())
-      ->GetRootWindowController()
+  RootWindowController::ForWindow(GetWidget()->GetNativeWindow())
       ->ConfigureWidgetInitParamsForContainer(
           user_dropdown_widget_.get(),
           kShellWindowId_DragImageAndTooltipContainer, &params);
   user_dropdown_widget_->Init(params);
 
   const SessionController* const session_controller =
       Shell::Get()->session_controller();
   const AddUserSessionPolicy add_user_policy =
       session_controller->GetAddUserPolicy();
   add_user_enabled_ = add_user_policy == AddUserSessionPolicy::ALLOWED;
@@ skipping 77 matching lines @@
   focus_manager_->RemoveFocusChangeListener(this);
   focus_manager_ = nullptr;
   if (user_card_container_->GetFocusManager())
     user_card_container_->GetFocusManager()->ClearFocus();
   user_card_view_->SetSuppressCaptureIcon(false);
   user_dropdown_widget_.reset();
 }
 
 }  // namespace tray
 }  // namespace ash