Make dragging outside the app list scroll back to its original position.

ui/app_list/views/apps_grid_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_APPS_GRID_VIEW_H_
 #define UI_APP_LIST_VIEWS_APPS_GRID_VIEW_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "base/timer/timer.h"
@@ skipping 255 matching lines @@
 
   // The point where the drag started in AppListItemView coordinates.
   gfx::Point drag_view_offset_;
 
   // The point where the drag started in GridView coordinates.
   gfx::Point drag_start_grid_view_;
 
   // The location of |drag_view_| when the drag started.
   gfx::Point drag_view_start_;
 
+  // Page the drag started on.
+  int drag_start_page_;
+
 #if defined(OS_WIN) && !defined(USE_AURA)
   // Created when a drag is started (ie: drag exceeds the drag threshold), but
   // not Run() until supplied with a shortcut path.
   scoped_refptr<SynchronousDrag> synchronous_drag_;
 #endif
 
   Pointer drag_pointer_;
   Index drop_target_;
 
   // An application target drag and drop host which accepts dnd operations.
@@ skipping 17 matching lines @@
   int page_flip_delay_in_ms_;
 
   views::BoundsAnimator bounds_animator_;
 
   DISALLOW_COPY_AND_ASSIGN(AppsGridView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_VIEWS_APPS_GRID_VIEW_H_