Print preview page selection should not require a rerendering of draft pages.

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 e5c67ecd7c75386c6acafc6707046b6b664ad59b..cf928156056ebe3a7c5108f3f70f5ca289446f66 100644
--- a/printing/print_job_constants.cc
+++ b/printing/print_job_constants.cc
@@ -30,6 +30,9 @@ const char kSettingDeviceName[] = "deviceName";
 // Print job duplex mode.
 const char kSettingDuplexMode[] = "duplex";
 
+// True, when a new set of draft preview data is required.
+const char kSettingGenerateDraftData[] = "generateDraftData";
+
 // Page orientation: true for landscape, false for portrait.
 const char kSettingLandscape[] = "landscape";