MacViews: Support -[NSWindow close] on sheets.

ui/views/cocoa/widget_owner_nswindow_adapter.mm

 // Copyright 2015 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.
 
 #import "ui/views/cocoa/widget_owner_nswindow_adapter.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "base/logging.h"
 #include "base/mac/sdk_forward_declarations.h"
@@ skipping 66 matching lines @@
 
 void WidgetOwnerNSWindowAdapter::OnWindowWillClose() {
   // Retain the child window before closing it. If the last reference to the
   // NSWindow goes away inside -[NSWindow close], then bad stuff can happen.
   // See e.g. http://crbug.com/616701.
   base::scoped_nsobject<NSWindow> child_window(child_->ns_window(),
                                                base::scoped_policy::RETAIN);
 
   // AppKit child window relationships break when the windows are not visible,
   // so if the child is not visible, it won't currently be a child.
-  DCHECK(![child_window isVisible] || [child_window parentWindow]);
+  if (![child_window isVisible])
+    DCHECK(![child_window parentWindow] && ![child_window sheetParent]);
   DCHECK([child_window delegate]);
 
   [child_window close];
   // Note: |this| will be deleted here.
 
   DCHECK(![child_window parentWindow]);
   DCHECK(![child_window delegate]);
 }
 
 void WidgetOwnerNSWindowAdapter::OnWindowDidChangeOcclusionState() {
@@ skipping 49 matching lines @@
   DCHECK_EQ(child, child_);
   [GetNSWindow() removeChildWindow:child->ns_window()];
   delete this;
 }
 
 WidgetOwnerNSWindowAdapter::~WidgetOwnerNSWindowAdapter() {
   [[NSNotificationCenter defaultCenter] removeObserver:observer_bridge_];
 }
 
 }  // namespace views