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 5e7863eedb87e621447d0e2a593dbe0e162139e7..0edea06abe467d8203fd34ad4c3fcefd8239d0fe 100644
--- a/printing/print_job_constants.cc
+++ b/printing/print_job_constants.cc
@@ -43,6 +43,9 @@ 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";
+
 // Option to print headers and Footers: true if selected, false if not.
 const char kSettingHeaderFooterEnabled[] = "headerFooterEnabled";