PrintPreview: Added code to honor the grayscale color model.

chrome/browser/printing/print_system_task_proxy.cc

Index: chrome/browser/printing/print_system_task_proxy.cc
diff --git a/chrome/browser/printing/print_system_task_proxy.cc b/chrome/browser/printing/print_system_task_proxy.cc
index c1811f5bff661fe03a8455e5682557c1a9bdbd30..e85e0fead3dde2486a9d55eaa9c4637e9e7a0458 100644
--- a/chrome/browser/printing/print_system_task_proxy.cc
+++ b/chrome/browser/printing/print_system_task_proxy.cc
@@ -148,6 +148,8 @@ bool getBasicColorModelSettings(
     *color_model_for_black = printing::BLACK;
   else if (ppdFindChoice(color_model, printing::kGray))
     *color_model_for_black = printing::GRAY;
+  else if (ppdFindChoice(color_model, printing::kGrayscale))
+    *color_model_for_black = printing::GRAYSCALE;
 
   if (ppdFindChoice(color_model, printing::kColor))
     *color_model_for_color = printing::COLOR;