After uninstall, remove last item in Launcher folder

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 0a8e0cd33bfc5b8b006eb65fd62d4dbaf375cb41..4c4d9b0d1f9ccc4ad8d82366302fb11b01fbdd54 100644
--- a/ui/app_list/app_list_model.cc
+++ b/ui/app_list/app_list_model.cc
@@ -219,6 +219,19 @@ bool AppListModel::MoveItemToFolderAt(AppListItem* item,
   return true;
 }
 
+void AppListModel::DeleteUninstalledItem(const std::string& id) {
+  AppListItem* item = FindItem(id);
+  if (!item)
+    return;
+  AppListFolderItem* folder = FindFolderItem(item->folder_id());
+  DeleteItem(id);
+
+  if (folder) {
+    FOR_EACH_OBSERVER(AppListModelObserver, observers_,
+                      OnAppListChildItemUninstalled(folder));
+  }
+}
+
 void AppListModel::SetItemPosition(AppListItem* item,
                                    const syncer::StringOrdinal& new_position) {
   if (!item->IsInFolder()) {