Moves maintaining root_window_for_new_windows_ to Shell

ash/root_window_controller.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/root_window_controller.h"
 
 #include <algorithm>
 #include <queue>
 #include <vector>
 
@@ skipping 1106 matching lines @@
   set_touch_hud_projection(new TouchHudProjection(GetRootWindow()));
 }
 
 void RootWindowController::DisableTouchHudProjection() {
   if (!touch_hud_projection_)
     return;
   touch_hud_projection_->Remove();
 }
 
 void RootWindowController::ResetRootForNewWindowsIfNecessary() {
-  WmShell* shell = WmShell::Get();
+  Shell* shell = Shell::GetInstance();
   // Change the target root window before closing child windows. If any child
   // being removed triggers a relayout of the shelf it will try to build a
   // window list adding windows from the target root window's containers which
   // may have already gone away.
   WmWindow* root = GetWindow();
   if (shell->GetRootWindowForNewWindows() == root) {
     // The root window for new windows is being destroyed. Switch to the primary
     // root window if possible.
-    WmWindow* primary_root = shell->GetPrimaryRootWindow();
+    WmWindow* primary_root = WmShell::Get()->GetPrimaryRootWindow();
     shell->set_root_window_for_new_windows(primary_root == root ? nullptr
                                                                 : primary_root);
   }
 }
 
 void RootWindowController::OnMenuClosed() {
   menu_runner_.reset();
   menu_model_adapter_.reset();
   menu_model_.reset();
   wm_shelf_->UpdateVisibilityState();
 }
 
 void RootWindowController::OnLoginStateChanged(LoginStatus status) {
   wm_shelf_->UpdateVisibilityState();
 }
 
 void RootWindowController::OnTouchHudProjectionToggled(bool enabled) {
   if (enabled)
     EnableTouchHudProjection();
   else
     DisableTouchHudProjection();
 }
 
 RootWindowController* GetRootWindowController(const aura::Window* root_window) {
   return root_window ? GetRootWindowSettings(root_window)->controller : nullptr;
 }
 
 }  // namespace ash