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

chrome/browser/printing/print_dialog_gtk.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/printing/print_dialog_gtk.h"
 
 #include <fcntl.h>
 #include <gtk/gtkpagesetupunixdialog.h>
 #include <gtk/gtkprintjob.h>
 #include <sys/stat.h>
@@ skipping 182 matching lines @@
         break;
       case printing::CMYK:
         color_mode = kCMYK;
         break;
       default:
         color_mode = kGrayscale;
         break;
     }
     gtk_print_settings_set(gtk_settings_, kCUPSColorModel, color_mode);
 
-    const char* cups_duplex_mode;
-    switch (duplex_mode) {
-      case printing::LONG_EDGE:
-        cups_duplex_mode = kDuplexNoTumble;
-        break;
-      case printing::SHORT_EDGE:
-        cups_duplex_mode = kDuplexTumble;
-        break;
-      default:
-        cups_duplex_mode = kDuplexNone;
-        break;
+    if (duplex_mode != printing::UNKNOWN_DUPLEX_MODE) {
+      const char* cups_duplex_mode;
+      switch (duplex_mode) {
+        case printing::LONG_EDGE:
+          cups_duplex_mode = kDuplexNoTumble;
+          break;
+        case printing::SHORT_EDGE:
+          cups_duplex_mode = kDuplexTumble;
+          break;
+        case printing::SIMPLEX:
+          cups_duplex_mode = kDuplexNone;
+          break;
+        default:  // UNKNOWN_DUPLEX_MODE
+          NOTREACHED();
+          break;
+      }
+      gtk_print_settings_set(gtk_settings_, kCUPSDuplex, cups_duplex_mode);
     }
-    gtk_print_settings_set(gtk_settings_, kCUPSDuplex, cups_duplex_mode);
   }
 
   gtk_print_settings_set_orientation(
       gtk_settings_,
       landscape ? GTK_PAGE_ORIENTATION_LANDSCAPE :
                   GTK_PAGE_ORIENTATION_PORTRAIT);
 
   InitPrintSettings(ranges);
   return true;
 }
@@ skipping 168 matching lines @@
   // Printing finished. Matches AddRef() in PrintDocument();
   Release();
 }
 
 void PrintDialogGtk::InitPrintSettings(const PageRanges& page_ranges) {
   PrintSettings settings;
   printing::PrintSettingsInitializerGtk::InitPrintSettings(
       gtk_settings_, page_setup_, page_ranges, false, &settings);
   context_->InitWithSettings(settings);
 }