Print Preview: Display a throbber when the user requests the system print

chrome/browser/printing/print_preview_tab_controller.cc

Index: chrome/browser/printing/print_preview_tab_controller.cc
diff --git a/chrome/browser/printing/print_preview_tab_controller.cc b/chrome/browser/printing/print_preview_tab_controller.cc
index 0d94be172f689e541f0bf6fe1d5f13e7c51cd1d1..b7e4bd7fd2010ef20d161485f15caef47b646d12 100644
--- a/chrome/browser/printing/print_preview_tab_controller.cc
+++ b/chrome/browser/printing/print_preview_tab_controller.cc
@@ -138,6 +138,10 @@ void PrintPreviewTabController::Observe(NotificationType type,
     if (initiator_tab)
       RemoveObservers(initiator_tab);
 
+    PrintPreviewUI* print_preview_ui =
+        static_cast<PrintPreviewUI*>(source_tab->web_ui());
+    print_preview_ui->OnNavigation();
+
     // Erase the map entry.
     preview_tab_map_.erase(source_tab);
   } else {