Remove more dead app list code.

ui/app_list/app_list_folder_item.cc

Index: ui/app_list/app_list_folder_item.cc
diff --git a/ui/app_list/app_list_folder_item.cc b/ui/app_list/app_list_folder_item.cc
index da2cc09de33d07bc6196aac4a584ff3e603d849b..d4ab28fc2d70a78b2f9fcff2c52fe47e64f92448 100644
--- a/ui/app_list/app_list_folder_item.cc
+++ b/ui/app_list/app_list_folder_item.cc
@@ -60,11 +60,6 @@ size_t AppListFolderItem::ChildItemCount() const {
   return item_list_->item_count();
 }
 
-void AppListFolderItem::OnExtensionPreferenceChanged() {
-  for (size_t i = 0; i < item_list_->item_count(); ++i)
-    item_list_->item_at(i)->OnExtensionPreferenceChanged();
-}
-
 bool AppListFolderItem::CompareForTest(const AppListItem* other) const {
   if (!AppListItem::CompareForTest(other))
     return false;