PrintPreview: Hide/Show the header footer option based on print frame margins.

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 c671326aa244e434045894d0f4fa24e2f3665664..cde24f70e09df1e0d8021806b46451e4ef1e4c90 100644
--- a/printing/print_job_constants.cc
+++ b/printing/print_job_constants.cc
@@ -113,6 +113,12 @@ const char kSettingPageRangeTo[] = "to";
 
 const char kSettingPreviewModifiable[] = "previewModifiable";
 
+// Keys that specifies the printable area details.
+const char kSettingPrintableAreaX[] = "printableAreaX";
+const char kSettingPrintableAreaY[] = "printableAreaY";
+const char kSettingPrintableAreaWidth[] = "printableAreaWidth";
+const char kSettingPrintableAreaHeight[] = "printableAreaHeight";
+
 // Printer name.
 const char kSettingPrinterName[] = "printerName";