Makes ChildModalWindow not leak

ash/test/child_modal_window.h

 // 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.
 
 #ifndef ASH_TEST_CHILD_MODAL_WINDOW_H_
 #define ASH_TEST_CHILD_MODAL_WINDOW_H_
 
+#include <memory>
+
 #include "base/macros.h"
 #include "ui/views/controls/button/button.h"
 #include "ui/views/widget/widget_delegate.h"
 #include "ui/views/widget/widget_observer.h"
 
 namespace views {
 class LabelButton;
 class NativeViewHost;
 class Textfield;
 class View;
 class Widget;
 }
 
 namespace ash {
 namespace test {
 
-void CreateChildModalParent(gfx::NativeView context);
+void CreateChildModalParent(aura::Window* context);
 
 class ChildModalParent : public views::WidgetDelegateView,
                          public views::ButtonListener,
                          public views::WidgetObserver {
  public:
-  ChildModalParent(gfx::NativeView context);
+  ChildModalParent(aura::Window* context);
   ~ChildModalParent() override;
 
   void ShowChild();
-  gfx::NativeWindow GetModalParent() const;
-  gfx::NativeWindow GetChild() const;
+  aura::Window* GetModalParent() const;
+  aura::Window* GetChild() const;
 
  private:
   views::Widget* CreateChild();
 
   // Overridden from views::WidgetDelegate:
   base::string16 GetWindowTitle() const override;
   bool CanResize() const override;
   void DeleteDelegate() override;
 
   // Overridden from views::View:
   void Layout() override;
   void ViewHierarchyChanged(
       const ViewHierarchyChangedDetails& details) override;
 
   // Overridden from ButtonListener:
   void ButtonPressed(views::Button* sender, const ui::Event& event) override;
 
   // Overridden from WidgetObserver:
   void OnWidgetDestroying(views::Widget* widget) override;
 
+  // This is the Widget this class creates to contain the child Views. This
+  // class is *not* the WidgetDelegateView for this Widget.
+  std::unique_ptr<views::Widget> widget_;
+
   // The button to toggle showing and hiding the child window. The child window
   // does not block input to this button.
   views::LabelButton* button_;
 
   // The text field to indicate the keyboard focus.
   views::Textfield* textfield_;
 
   // The host for the modal parent.
   views::NativeViewHost* host_;
 
-  // The modal parent of the child window. The child window blocks input to this
-  // view.
-  gfx::NativeWindow modal_parent_;
-
   // The child window.
   views::Widget* child_;
 
   DISALLOW_COPY_AND_ASSIGN(ChildModalParent);
 };
 
 }  // namespace test
 }  // namespace ash
 
 #endif  // ASH_TEST_CHILD_MODAL_WINDOW_H_