Prevent SSL certificate export from jamming the chrome.

chrome/browser/ui/views/certificate_viewer_win.cc

 // Copyright (c) 2011 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 "chrome/browser/certificate_viewer.h"
 
 #include <windows.h>
 #include <cryptuiapi.h>
 #pragma comment(lib, "cryptui.lib")
 
@@ skipping 25 matching lines @@
   HCERTSTORE cert_store = cert_list->hCertStore;
   view_info.cStores = 1;
   view_info.rghStores = &cert_store;
   BOOL properties_changed;
 
   // We must allow nested tasks to dispatch so that, e.g. gpu tasks are
   // processed for painting. This allows a second window to continue painting
   // while the the certificate dialog is open.
   base::MessageLoop::ScopedNestableTaskAllower allow(
       base::MessageLoop::current());
+
+  // Tell the message loop to only handle certain types of messages while the
+  // dialog is open to avoid bad things happening. See https://crbug.com/344012
+  // for details.
+  base::MessageLoop::current()->set_os_modal_loop(true);
   // This next call blocks but keeps processing windows messages, making it
   // modal to the browser window.
   ::CryptUIDlgViewCertificate(&view_info, &properties_changed);
 
+  base::MessageLoop::current()->set_os_modal_loop(false);
   CertFreeCertificateContext(cert_list);
 }
 
 }  // namespace
 
 void ShowCertificateViewer(content::WebContents* web_contents,
                            gfx::NativeWindow parent,
                            net::X509Certificate* cert) {
   if (chrome::GetHostDesktopTypeForNativeWindow(parent) !=
       chrome::HOST_DESKTOP_TYPE_ASH) {
     ShowCertificateViewerImpl(
         web_contents,
         parent->GetHost()->GetAcceleratedWidget(), cert);
   } else {
     NOTIMPLEMENTED();
   }
 }