After uninstall, remove last item in Launcher folder

ui/app_list/app_list_model.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef UI_APP_LIST_APP_LIST_MODEL_H_
 #define UI_APP_LIST_APP_LIST_MODEL_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 107 matching lines @@
 
   // Sets the name and short name of |item| and notifies observers.
   void SetItemNameAndShortName(AppListItem* item,
                                const std::string& name,
                                const std::string& short_name);
 
   // Deletes the item matching |id| from |top_level_item_list_| or from the
   // appropriate folder.
   void DeleteItem(const std::string& id);
 
+  // Wrapper around DeleteItem() which will also clean up if its parent folder
+  // has a single child left.
+  void DeleteUninstalledItem(const std::string& id);
+
   // Call OnExtensionPreferenceChanged() for all items in the model.
   void NotifyExtensionPreferenceChanged();
 
   // Sets whether or not the folder UI should be enabled. If |folders_enabled|
   // is false, removes any non-OEM folders.
   void SetFoldersEnabled(bool folders_enabled);
 
   // Sets whether or not the custom launcher page should be enabled.
   void SetCustomLauncherPageEnabled(bool enabled);
   bool custom_launcher_page_enabled() const {
@@ skipping 86 matching lines @@
 
   // The current number of subpages the custom launcher page has pushed.
   int custom_launcher_page_subpage_depth_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListModel);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_APP_LIST_MODEL_H_