Use document from preview for System Dialog printing on Windows.

chrome/browser/printing/print_job_worker.h

Index: chrome/browser/printing/print_job_worker.h
diff --git a/chrome/browser/printing/print_job_worker.h b/chrome/browser/printing/print_job_worker.h
index c3c9cf51b04699549aa258640186ef5835307b70..1cc9d069bf172825af47517eb222e4a7adf52654 100644
--- a/chrome/browser/printing/print_job_worker.h
+++ b/chrome/browser/printing/print_job_worker.h
@@ -54,7 +54,9 @@ class PrintJobWorker {
 
   // Set the new print settings. This function takes ownership of

[Noam Samuel, 2014/08/20 00:04:17]

Nit: Second part of comment no longer necessary.

[Vitaly Buka (NO REVIEWS), 2014/08/20 02:42:55]

Done.

   // |new_settings|.
-  void SetSettings(const base::DictionaryValue* const new_settings);
+  void SetSettings(
+      scoped_ptr<PrintingUIWebContentsObserver> web_contents_observer,
+      scoped_ptr<base::DictionaryValue> new_settings);
 
   // Starts the printing loop. Every pages are printed as soon as the data is
   // available. Makes sure the new_document is the right one.
@@ -124,7 +126,9 @@ class PrintJobWorker {
 
   // Called on the UI thread to update the print settings. This function takes
   // the ownership of |new_settings|.
-  void UpdatePrintSettings(const base::DictionaryValue* const new_settings);
+  void UpdatePrintSettings(
+      scoped_ptr<PrintingUIWebContentsObserver> web_contents_observer,
+      scoped_ptr<base::DictionaryValue> new_settings);
 
   // Reports settings back to owner_.
   void GetSettingsDone(PrintingContext::Result result);