Block nested system print dialogs on Windows

printing/printing_context_system_dialog_win.cc

 // 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.
 
 #include "printing/printing_context_system_dialog_win.h"
 
+#include "base/auto_reset.h"
 #include "base/message_loop/message_loop.h"
 #include "printing/backend/win_helper.h"
 #include "printing/print_settings_initializer_win.h"
 #include "skia/ext/platform_device.h"
 
 namespace printing {
 
 PrintingContextSytemDialogWin::PrintingContextSytemDialogWin(Delegate* delegate)
     : PrintingContextWin(delegate), dialog_box_(NULL) {
 }
@@ skipping 60 matching lines @@
 
 void PrintingContextSytemDialogWin::Cancel() {
   PrintingContextWin::Cancel();
   if (dialog_box_) {
     DestroyWindow(dialog_box_);
     dialog_box_dismissed_ = true;
   }
 }
 
 HRESULT PrintingContextSytemDialogWin::ShowPrintDialog(PRINTDLGEX* options) {
+  // Runs always on the UI thread.
+  static bool is_dialog_shown = false;
+  if (is_dialog_shown)
+    return E_FAIL;
+  // Block opening dialog from nested task. It crashes PrintDlgEx.
+  base::AutoReset<bool> auto_reset(&is_dialog_shown, true);
+
   // Note that this cannot use ui::BaseShellDialog as the print dialog is
   // system modal: opening it from a background thread can cause Windows to
   // get the wrong Z-order which will make the print dialog appear behind the
   // browser frame (but still being modal) so neither the browser frame nor
   // the print dialog will get any input. See http://crbug.com/342697
   // http://crbug.com/180997 for details.
   base::MessageLoop::ScopedNestableTaskAllower allow(
       base::MessageLoop::current());
 
   return PrintDlgEx(options);
@@ skipping 164 matching lines @@
 
   if (dialog_options.hDevMode != NULL)
     GlobalFree(dialog_options.hDevMode);
   if (dialog_options.hDevNames != NULL)
     GlobalFree(dialog_options.hDevNames);
 
   return context() ? OK : FAILED;
 }
 
 }  // namespace printing