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

chrome/browser/ui/cocoa/certificate_viewer_mac_cocoa.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.
 
 #import "chrome/browser/ui/cocoa/certificate_viewer_mac_cocoa.h"
 
 #include "base/logging.h"
 #import "base/mac/foundation_util.h"
 #include "chrome/browser/certificate_viewer.h"
 #import "chrome/browser/ui/cocoa/constrained_window/constrained_window_mac.h"
@@ skipping 81 matching lines @@
   [self closeCertificateSheet];
 }
 
 - (void)hideSheet {
   NSWindow* sheetWindow = [overlayWindow_ attachedSheet];
   [sheetWindow setAlphaValue:0.0];
   [sheetWindow setIgnoresMouseEvents:YES];
 
   oldResizesSubviews_ = [[sheetWindow contentView] autoresizesSubviews];
   [[sheetWindow contentView] setAutoresizesSubviews:NO];
+
+  // Ensure this overlay doesn't interfere with overlays with hidden sheets.
+  [overlayWindow_ setLevel:0];
 }
 
 - (void)unhideSheet {
   NSWindow* sheetWindow = [overlayWindow_ attachedSheet];
   [sheetWindow setIgnoresMouseEvents:NO];
 
   [[sheetWindow contentView] setAutoresizesSubviews:oldResizesSubviews_];
   [[overlayWindow_ attachedSheet] setAlphaValue:1.0];
+
+  // Set the current overlay's level higher than overlays with hidden sheets.
+  [overlayWindow_ setLevel:1];
 }
 
 - (void)pulseSheet {
   // NOOP
 }
 
 - (void)makeSheetKeyAndOrderFront {
   [[overlayWindow_ attachedSheet] makeKeyAndOrderFront:nil];
 }
 
@@ skipping 13 matching lines @@
 
 void ShowCertificateViewer(content::WebContents* web_contents,
                            gfx::NativeWindow parent,
                            net::X509Certificate* cert) {
   // SSLCertificateViewerCocoa will manage its own lifetime and will release
   // itself when the dialog is closed.
   // See -[SSLCertificateViewerCocoa onConstrainedWindowClosed].
   [[SSLCertificateViewerCocoa alloc] initWithCertificate:cert
                                           forWebContents:web_contents];
 }