Cleanup: Fix some misc nits in printing code.

chrome/browser/printing/print_preview_context_menu_observer.cc

Index: chrome/browser/printing/print_preview_context_menu_observer.cc
diff --git a/chrome/browser/printing/print_preview_context_menu_observer.cc b/chrome/browser/printing/print_preview_context_menu_observer.cc
index b9c2a02f160c0dcc8780482839e2f8e6fe19bc45..eca5d02fb453f6865c0c6fe535939858e54e3681 100644
--- a/chrome/browser/printing/print_preview_context_menu_observer.cc
+++ b/chrome/browser/printing/print_preview_context_menu_observer.cc
@@ -20,7 +20,7 @@ bool PrintPreviewContextMenuObserver::IsPrintPreviewDialog() {
       printing::PrintPreviewDialogController::GetInstance();
   if (!controller)
     return false;
-  return (controller->GetPrintPreviewForContents(contents_) != NULL);
+  return (controller->GetPrintPreviewForContents(contents_) != nullptr);
 }
 
 bool PrintPreviewContextMenuObserver::IsCommandIdSupported(int command_id) {