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 0c50b442f923cc66040148f9f61d8db24b46dfbf..dc864e692e3e7676a551f3c2ac9d5457909b424c 100644
--- a/printing/print_job_constants.cc
+++ b/printing/print_job_constants.cc
@@ -27,6 +27,9 @@ 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";