Converts MruWindowTracker to work with common types

ash/wm/ash_focus_rules.h

 // 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.
 
 #ifndef ASH_WM_ASH_FOCUS_RULES_H_
 #define ASH_WM_ASH_FOCUS_RULES_H_
 
 #include "ash/ash_export.h"
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "ui/wm/core/base_focus_rules.h"
 
 namespace ash {
 namespace wm {
 
 class ASH_EXPORT AshFocusRules : public ::wm::BaseFocusRules {
  public:
   AshFocusRules();
   ~AshFocusRules() override;
 
   // Tests if the given |window| can be activated, ignoring the system modal
   // dialog state.
   bool IsWindowConsideredActivatable(aura::Window* window) const;
 
  private:
   // ::wm::BaseFocusRules:
+  bool IsToplevelWindow(aura::Window* window) const override;
   bool SupportsChildActivation(aura::Window* window) const override;
   bool IsWindowConsideredVisibleForActivation(
       aura::Window* window) const override;
   bool CanActivateWindow(aura::Window* window) const override;
   aura::Window* GetNextActivatableWindow(aura::Window* ignore) const override;
 
   aura::Window* GetTopmostWindowToActivateForContainerIndex(
       int index,
       aura::Window* ignore) const;
   aura::Window* GetTopmostWindowToActivateInContainer(
       aura::Window* container,
       aura::Window* ignore) const;
 
   DISALLOW_COPY_AND_ASSIGN(AshFocusRules);
 };
 
 }  // namespace wm
 }  // namespace ash
 
 #endif  // ASH_WM_ASH_FOCUS_RULES_H_