MacViews: Be robust against Views manipulating Layers during Widget::Close().

ui/views/cocoa/bridged_native_widget.mm

 // 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.
 
 #import "ui/views/cocoa/bridged_native_widget.h"
 
 #import <objc/runtime.h>
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 1028 matching lines @@
   native_widget_mac_->GetWidget()->ReorderNativeViews();
 }
 
 void BridgedNativeWidget::ClearAssociationForView(const views::View* view) {
   auto it = associated_views_.find(view);
   DCHECK(it != associated_views_.end());
   associated_views_.erase(it);
 }
 
 void BridgedNativeWidget::ReorderChildViews() {
+  // Ignore layer manipulation during a Close(). This can be reached during the
+  // orderOut: in Close(), which notifies visibility changes to Views.
+  if (!bridged_view_)
+    return;
+
   RankMap rank;
   Widget* widget = native_widget_mac_->GetWidget();
   RankNSViews(widget->GetRootView(), associated_views_, &rank);
   // Unassociated NSViews should be ordered above associated ones. The exception
   // is the UI compositor's superview, which should always be on the very
   // bottom, so give it an explicit negative rank.
   if (compositor_superview_)
     rank[compositor_superview_] = -1;
   [bridged_view_ sortSubviewsUsingFunction:&SubviewSorter context:&rank];
 }
@@ skipping 359 matching lines @@
   [bridged_view_ setMouseDownCanMoveWindow:draggable];
   // AppKit will not update its cache of mouseDownCanMoveWindow unless something
   // changes. Previously we tried adding an NSView and removing it, but for some
   // reason it required reposting the mouse-down event, and didn't always work.
   // Calling the below seems to be an effective solution.
   [window_ setMovableByWindowBackground:NO];
   [window_ setMovableByWindowBackground:YES];
 }
 
 }  // namespace views