MacViews: Suppress visibility changes during an asynchronous close.

ui/views/widget/native_widget_mac.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 UI_VIEWS_WIDGET_NATIVE_WIDGET_MAC_H_
 #define UI_VIEWS_WIDGET_NATIVE_WIDGET_MAC_H_
 
 #include "base/macros.h"
 #include "ui/gfx/native_widget_types.h"
 #include "ui/views/widget/native_widget_private.h"
@@ skipping 15 matching lines @@
 class VIEWS_EXPORT NativeWidgetMac : public internal::NativeWidgetPrivate {
  public:
   explicit NativeWidgetMac(internal::NativeWidgetDelegate* delegate);
   ~NativeWidgetMac() override;
 
   // Retrieves the bridge associated with the given NSWindow. Returns null if
   // the supplied handle has no associated Widget.
   static BridgedNativeWidget* GetBridgeForNativeWindow(
       gfx::NativeWindow window);
 
-  // Return true if the delegate's modal type is window-modal. These display as
-  // a native window "sheet", and have a different lifetime to regular windows.
-  bool IsWindowModalSheet() const;
-
   // Deletes |bridge_| and informs |delegate_| that the native widget is
   // destroyed. This is usually called from the NSWindowDelegate.
   void OnWindowWillClose();
 
   // Returns the vertical position that sheets should be anchored, in pixels
   // from the bottom of the window.
   virtual int SheetPositionY();
 
   // internal::NativeWidgetPrivate:
   void InitNativeWidget(const Widget::InitParams& params) override;
@@ skipping 103 matching lines @@
 
   // Internal name.
   std::string name_;
 
   DISALLOW_COPY_AND_ASSIGN(NativeWidgetMac);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_WIDGET_NATIVE_WIDGET_MAC_H_