Add support to send print preset options in one message

printing/print_job_constants.h

 // Copyright (c) 2012 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 "build/build_config.h"
 #include "printing/printing_export.h"
 
@@ skipping 73 matching lines @@
 PRINTING_EXPORT extern const char kRGBA[];
 PRINTING_EXPORT extern const char kRGB16[];
 #endif
 
 // Print job duplex mode values.
 enum DuplexMode {
   UNKNOWN_DUPLEX_MODE = -1,
   SIMPLEX,
   LONG_EDGE,
   SHORT_EDGE,
+  DUPLEX_MODE_LAST = 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.
@@ skipping 32 matching lines @@
   DEFAULT_MARGINS,  // Default varies depending on headers being enabled or not
   NO_MARGINS,
   PRINTABLE_AREA_MARGINS,
   CUSTOM_MARGINS,
   MARGIN_TYPE_LAST = CUSTOM_MARGINS
 };
 
 }  // namespace printing
 
 #endif  // PRINTING_PRINT_JOB_CONSTANTS_H_