Remove more dead app list code.

ui/app_list/app_list_model.cc

Index: ui/app_list/app_list_model.cc
diff --git a/ui/app_list/app_list_model.cc b/ui/app_list/app_list_model.cc
index 38c2d5cf6da92f4c6a9b0547a23f5543c34fc26f..cb001bc0bf18f623fc80ebd005a10940f1b11668 100644
--- a/ui/app_list/app_list_model.cc
+++ b/ui/app_list/app_list_model.cc
@@ -292,11 +292,6 @@ void AppListModel::DeleteUninstalledItem(const std::string& id) {
   }
 }
 
-void AppListModel::NotifyExtensionPreferenceChanged() {
-  for (size_t i = 0; i < top_level_item_list_->item_count(); ++i)
-    top_level_item_list_->item_at(i)->OnExtensionPreferenceChanged();
-}
-
 void AppListModel::SetFoldersEnabled(bool folders_enabled) {
   folders_enabled_ = folders_enabled;
   if (folders_enabled)