Added back button when in folder view.

ui/app_list/views/contents_view.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_VIEWS_CONTENTS_VIEW_H_
 #define UI_APP_LIST_VIEWS_CONTENTS_VIEW_H_
 
 #include <map>
 #include <memory>
 #include <utility>
@@ skipping 186 matching lines @@
 
   // Maps State onto |view_model_| indices.
   std::map<AppListModel::State, int> state_to_view_;
 
   // Maps |view_model_| indices onto State.
   std::map<int, AppListModel::State> view_to_state_;
 
   // The page that was showing before ShowSearchResults(true) was invoked.
   int page_before_search_;
 
+  // Whether the fullscreen app list feature is active.
+  const bool is_fullscreen_app_list_enabled_;
+
   // Manages the pagination for the launcher pages.
   PaginationModel pagination_model_;
 
   DISALLOW_COPY_AND_ASSIGN(ContentsView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_CONTENTS_VIEW_H_