Centralizes more shared code between ash and mash

ash/aura/wm_root_window_controller_aura.h

 // 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.
 
 #ifndef ASH_AURA_WM_ROOT_CONTROLLER_AURA_H_
 #define ASH_AURA_WM_ROOT_CONTROLLER_AURA_H_
 
 #include "ash/ash_export.h"
 #include "ash/common/wm_root_window_controller.h"
 #include "base/macros.h"
@@ skipping 14 matching lines @@
 
   static WmRootWindowControllerAura* Get(aura::Window* window) {
     return const_cast<WmRootWindowControllerAura*>(
         Get(const_cast<const aura::Window*>(window)));
   }
   static const WmRootWindowControllerAura* Get(const aura::Window* window);
 
   // WmRootWindowController:
   bool HasShelf() override;
   WmShell* GetShell() override;
-  AlwaysOnTopController* GetAlwaysOnTopController() override;
   WmShelf* GetShelf() override;
   WmWindow* GetWindow() override;
   void ConfigureWidgetInitParamsForContainer(
       views::Widget* widget,
       int shell_container_id,
       views::Widget::InitParams* init_params) override;
   WmWindow* FindEventTarget(const gfx::Point& location_in_screen) override;
   gfx::Point GetLastMouseLocationInRoot() override;
   void OnInitialWallpaperAnimationStarted() override;
   void OnWallpaperAnimationFinished(views::Widget* widget) override;
 
+ protected:
+  // WmRootWindowController:
+  bool ShouldDestroyWindowInCloseChildWindows(WmWindow* window) override;
+
  private:
   friend class RootWindowController;
 
   RootWindowController* root_window_controller_;
 
   DISALLOW_COPY_AND_ASSIGN(WmRootWindowControllerAura);
 };
 
 }  // namespace ash
 
 #endif  // ASH_AURA_WM_ROOT_CONTROLLER_AURA_H_