MacViews: Attach child windows when parent is on the screen.

ui/views/cocoa/bridged_native_widget.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_COCOA_BRIDGED_NATIVE_WIDGET_H_
 #define UI_VIEWS_COCOA_BRIDGED_NATIVE_WIDGET_H_
 
 #import <Cocoa/Cocoa.h>
 
 #include <memory>
@@ skipping 124 matching lines @@
 
   // Called once by the NSWindowDelegate when the position of the window has
   // changed.
   void OnPositionChanged();
 
   // Called by the NSWindowDelegate when the visibility of the window may have
   // changed. For example, due to a (de)miniaturize operation, or the window
   // being reordered in (or out of) the screen list.
   void OnVisibilityChanged();
 
-  // Explicitly set the visibility. This is called when Cocoa requests a draw,
-  // but hasn't updated the value of -[NSWindow isVisible] yet.
-  void OnVisibilityChangedTo(bool new_visibility);
-
   // Called by the NSWindowDelegate on a scale factor or color space change.
   void OnBackingPropertiesChanged();
 
   // Called by the NSWindowDelegate when the window becomes or resigns key.
   void OnWindowKeyStatusChangedTo(bool is_key);
 
   // Called by NSWindowDelegate when the application receives a mouse-down, but
   // before the event is processed by NSWindows. Returning true here will cause
   // the event to be cancelled and reposted at the CGSessionEventTap level. This
   // is used to determine whether a mouse-down should drag the window.
@@ skipping 157 matching lines @@
   bool invalidate_shadow_on_frame_swap_ = false;
 
   AssociatedViews associated_views_;
 
   DISALLOW_COPY_AND_ASSIGN(BridgedNativeWidget);
 };
 
 }  // namespace views
 
 #endif  // UI_VIEWS_COCOA_BRIDGED_NATIVE_WIDGET_H_