Refactor AddScrollListItem() in system menu detailed views

ash/system/ime_menu/ime_list_view.h

Index: ash/system/ime_menu/ime_list_view.h
diff --git a/ash/system/ime_menu/ime_list_view.h b/ash/system/ime_menu/ime_list_view.h
index 2acb4e0bdb7885f9801cbff1bc0931bd4330af1d..b0c9d9fee58c64b57336a117fce493d00ace5a9d 100644
--- a/ash/system/ime_menu/ime_list_view.h
+++ b/ash/system/ime_menu/ime_list_view.h
@@ -44,6 +44,9 @@ class ImeListView : public TrayDetailsView {
   // Closes the view.
   void CloseImeListView();
 
+  // Scrolls contents such that |item_view| is visible.
+  void ScrollItemToVisible(views::View* item_view);
+
   void set_last_item_selected_with_keyboard(
       bool last_item_selected_with_keyboard) {
     last_item_selected_with_keyboard_ = last_item_selected_with_keyboard;