Added back button when in folder view.

ui/app_list/views/app_list_view.cc

 // 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.
 
 #include "ui/app_list/views/app_list_view.h"
 
 #include <algorithm>
 
 #include "base/command_line.h"
 #include "base/macros.h"
@@ skipping 828 matching lines @@
           new_widget_bounds.set_y(half_app_list_y);
           break;
         }
         case FULLSCREEN_SEARCH:
         case FULLSCREEN_ALL_APPS:
         case CLOSED:
           NOTREACHED();
           break;
       }
       break;
-    case FULLSCREEN_ALL_APPS:
+    case FULLSCREEN_ALL_APPS: {
       new_widget_bounds.set_y(0);
+      AppsContainerView* apps_container_view =
+          app_list_main_view_->contents_view()->apps_container_view();
+
+      if (apps_container_view->IsInFolderView())
+        apps_container_view->app_list_folder_view()->CloseFolderPage();
+
       app_list_main_view_->contents_view()->SetActiveState(
           AppListModel::STATE_APPS);
       break;
+    }
     case FULLSCREEN_SEARCH:
       new_widget_bounds.set_y(0);
       break;
     case CLOSED:
       app_list_main_view_->Close();
       delegate_->Dismiss();
       break;
   }
   fullscreen_widget_->SetBounds(new_widget_bounds);
   app_list_state_ = new_state_override;
@@ skipping 94 matching lines @@
                        .work_area()
                        .size();
   size.Enlarge(0, kShelfSize);
   fullscreen_widget_->SetSize(size);
 
   // Update the |fullscreen_widget_| bounds to accomodate the new work area.
   SetState(app_list_state_);
 }
 
 }  // namespace app_list