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

printing/print_job_constants.cc

Index: printing/print_job_constants.cc
diff --git a/printing/print_job_constants.cc b/printing/print_job_constants.cc
index 0edea06abe467d8203fd34ad4c3fcefd8239d0fe..ed3362cd3483b53eed4f4511b2cdef1125cac5e1 100644
--- a/printing/print_job_constants.cc
+++ b/printing/print_job_constants.cc
@@ -40,8 +40,8 @@ const char kSettingDefaultMarginsSelected[] = "defaultMarginsSelected";
 // Device name: Unique printer identifier.
 const char kSettingDeviceName[] = "deviceName";
 
-// Print job duplex mode.
-const char kSettingDuplexMode[] = "duplex";
+// Duplex mode information
+const char kSettingDuplexModeInfo[] = "duplexInfo";
 
 // True, when a new set of draft preview data is required.
 const char kSettingGenerateDraftData[] = "generateDraftData";
@@ -108,12 +108,18 @@ const char kSettingPageRangeFrom[] = "from";
 // The last page of a page range. (1-based)
 const char kSettingPageRangeTo[] = "to";
 
+// Key to identify the printer default duplex value.
+const char kPrinterDefaultDuplexValue[] = "printerDefaultDuplexValue";
+
 // Printer name.
 const char kSettingPrinterName[] = "printerName";
 
 // Print to PDF option: true if selected, false if not.
 const char kSettingPrintToPDF[] = "printToPDF";
 
+// Key to identify the user selected duplex value.
+const char kUserSelectedDuplexValue[] = "userSelectedDuplexValue";
+
 // Indices used to represent first preview page and complete preview document.
 const int FIRST_PAGE_INDEX = 0;
 const int COMPLETE_PREVIEW_DOCUMENT_INDEX = -1;