Add Vector2d classes that represent offsets, instead of using Point.

ui/app_list/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_APPS_GRID_VIEW_H_
 #define UI_APP_LIST_APPS_GRID_VIEW_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 165 matching lines @@
   gfx::Size icon_size_;
   int cols_;
   int rows_per_page_;
 
   // Tracks app item views. There is a view per item in |model_|.
   views::ViewModel view_model_;
 
   views::View* selected_view_;
 
   views::View* drag_view_;
-  gfx::Point drag_offset_;
+  gfx::Point drag_start_;
   Pointer drag_pointer_;
   Index drop_target_;
 
   gfx::Point last_drag_point_;
 
   // Timer to auto flip page when dragging an item near the left/right edges.
   base::OneShotTimer<AppsGridView> page_flip_timer_;
 
   // Target page to switch to when |page_flip_timer_| fires.
   int page_flip_target_;
 
   // Delay in milliseconds of when |page_flip_timer_| should fire after user
   // drags an item near the edges.
   int page_flip_delay_in_ms_;
 
   views::BoundsAnimator bounds_animator_;
 
   DISALLOW_COPY_AND_ASSIGN(AppsGridView);
 };
 
 }  // namespace app_list
 
 #endif  // UI_APP_LIST_APPS_GRID_VIEW_H_