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

chrome/browser/ui/panels/panel_drag_controller.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 CHROME_BROWSER_UI_PANELS_PANEL_DRAG_CONTROLLER_H_
 #define CHROME_BROWSER_UI_PANELS_PANEL_DRAG_CONTROLLER_H_
 
 #include <set>
 #include "base/basictypes.h"
 #include "ui/gfx/point.h"
@@ skipping 58 matching lines @@
 
   // The original panel strip when the drag is started.
   PanelStrip* dragging_panel_original_strip_;
 
   // The mouse location, in screen coordinates, when StartDragging or Drag was
   // pveviously called.
   gfx::Point last_mouse_location_;
 
   // The offset from mouse location to the panel position when the drag
   // starts.
-  gfx::Point offset_from_mouse_location_on_drag_start_;
+  gfx::Vector2d offset_from_mouse_location_on_drag_start_;
 
   // The minimum distance that the docked panel gets dragged up in order to
   // make it free-floating.
   static const int kDetachDockedPanelThreshold;
 
   // Indicates how close the bottom of the detached panel is to the bottom of
   // the docked area such that the detached panel becomes docked.
   static const int kDockDetachedPanelThreshold;
 
   DISALLOW_COPY_AND_ASSIGN(PanelDragController);
 };
 
 #endif  // CHROME_BROWSER_UI_PANELS_PANEL_DRAG_CONTROLLER_H_