After uninstall, remove last item in Launcher folder

ui/app_list/views/app_list_main_view.h

 // Copyright 2013 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_VIEWS_APP_LIST_MAIN_VIEW_H_
 #define UI_APP_LIST_VIEWS_APP_LIST_MAIN_VIEW_H_
 
 #include <string>
 
 #include "base/memory/scoped_vector.h"
@@ skipping 59 matching lines @@
   // Returns true if the app list should be centered and in landscape mode.
   bool ShouldCenterWindow() const;
 
   // Called when the search box's visibility is changed.
   void NotifySearchBoxVisibilityChanged();
 
   bool ShouldShowCustomLauncherPage() const;
   void UpdateCustomLauncherPageVisibility();
 
   // Overridden from AppListModelObserver:
+  void OnSingleItemFolderWillBeDeleted() override;
   void OnCustomLauncherPageEnabledStateChanged(bool enabled) override;
   void OnSearchEngineIsGoogleChanged(bool is_google) override;
 
  private:
   class IconLoader;
 
   // Adds the ContentsView.
   void AddContentsViews();
 
   // Gets the PaginationModel owned by the AppsGridView.
@@ skipping 38 matching lines @@
   ScopedVector<IconLoader> pending_icon_loaders_;
 
   base::WeakPtrFactory<AppListMainView> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AppListMainView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_APP_LIST_MAIN_VIEW_H_