PrintPreview: Added code to identify the printer default duplex value.

printing/print_job_constants.h

 // 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.
 
 #ifndef PRINTING_PRINT_JOB_CONSTANTS_H_
 #define PRINTING_PRINT_JOB_CONSTANTS_H_
 
 #include "printing/printing_export.h"
 
 namespace printing {
@@ skipping 31 matching lines @@
 PRINTING_EXPORT extern const char kSettingPageRangeFrom[];
 PRINTING_EXPORT extern const char kSettingPageRangeTo[];
 PRINTING_EXPORT extern const char kSettingPrinterName[];
 PRINTING_EXPORT extern const char kSettingPrintToPDF[];
 
 PRINTING_EXPORT extern const int FIRST_PAGE_INDEX;
 PRINTING_EXPORT extern const int COMPLETE_PREVIEW_DOCUMENT_INDEX;
 
 // Print job duplex mode values.
 enum DuplexMode {
+  UNKNOWN_DUPLEX_MODE = -1,
   SIMPLEX,
   LONG_EDGE,
   SHORT_EDGE,
 };
 
 // Specifies the horizontal alignment of the headers and footers.
 enum HorizontalHeaderFooterPosition {
   LEFT,
   CENTER,
   RIGHT
 };
 
 // Specifies the vertical alignment of the Headers and Footers.
 enum VerticalHeaderFooterPosition {
   TOP,
   BOTTOM
 };
 
 // Print job color mode values.
 enum ColorMode {
   GRAY = 1,
   COLOR,
   CMYK,
 };
 
 }  // namespace printing
 
 #endif  // PRINTING_PRINT_JOB_CONSTANTS_H_