Mac: Fix window ordering for certificate viewer/selector sheets and overlays.

components/constrained_window/native_web_contents_modal_dialog_manager_views_mac.mm

 // Copyright 2016 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.
 
 #include "components/constrained_window/native_web_contents_modal_dialog_manager_views_mac.h"
 
 #import <Cocoa/Cocoa.h>
 
 #include "components/constrained_window/constrained_window_views.h"
 #include "components/guest_view/browser/guest_view_base.h"
 #include "components/web_modal/web_contents_modal_dialog_manager.h"
 #include "content/public/browser/web_contents.h"
 #import "ui/gfx/mac/coordinate_conversion.h"
 #include "ui/views/widget/widget.h"
 #include "ui/views/widget/widget_delegate.h"
 
 using web_modal::WebContentsModalDialogManager;
 using web_modal::SingleWebContentsDialogManager;
 
 namespace {
 
 // Sets visibility and mouse events for a Cocoa NSWindow* and an attached sheet.
 void SetSheetVisible(gfx::NativeWindow overlay, bool visible) {
-  CGFloat alpha = visible ? 1.0 : 0.0;
   BOOL ignore_events = visible ? NO : YES;
 
   // Don't allow interaction with the tab underneath the overlay.
   [overlay setIgnoresMouseEvents:ignore_events];
 
-  [[overlay attachedSheet] setAlphaValue:alpha];
+  [[overlay attachedSheet] setAlphaValue:visible ? 1.0 : 0.0];
   [[overlay attachedSheet] setIgnoresMouseEvents:ignore_events];
+
+  if (visible) {
+    // When showing the sheet, re-order the overlay and sheet to be on top of
+    // any other sheet/overlay pairs which may be open at the same time. Without
+    // doing this, the sheet and overlay become obscured behind overlays for
+    // other sheets, which block mouse events intended for the current sheet.
+    NSWindow* parent = [overlay parentWindow];
+    [parent removeChildWindow:overlay];
+    [parent addChildWindow:overlay ordered:NSWindowAbove];
+    [overlay removeChildWindow:[overlay attachedSheet]];
+    [overlay addChildWindow:[overlay attachedSheet] ordered:NSWindowAbove];
+  }
 }
 
 }  // namespace
 
 namespace constrained_window {
 
 NativeWebContentsModalDialogManagerViewsMac::
     NativeWebContentsModalDialogManagerViewsMac(
         gfx::NativeWindow dialog,
         web_modal::SingleWebContentsDialogManagerDelegate* native_delegate)
@@ skipping 47 matching lines @@
 void NativeWebContentsModalDialogManagerViewsMac::HideWidget(
     views::Widget* widget) {
   NSWindow* dialog_window = widget->GetNativeWindow();
   // Avoid views::Widget::Hide(), as a call to orderOut: on a NSWindow with an
   // attached sheet will close the sheet. Instead, just set the sheet to 0
   // opacity and don't accept click events.
   SetSheetVisible(dialog_window, false);
 }
 
 }  // namespace constrained_window