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

ui/gfx/rect.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/gfx/rect.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #elif defined(TOOLKIT_GTK)
 #include <gdk/gdk.h>
 #endif
 
 #include "base/logging.h"
 #include "base/stringprintf.h"
 #include "ui/gfx/insets.h"
 #include "ui/gfx/rect_base_impl.h"
 
 namespace gfx {
 
-template class RectBase<Rect, Point, Size, Insets, int>;
+template class RectBase<Rect, Point, Size, Insets, Vector2d, int>;
 
-typedef class RectBase<Rect, Point, Size, Insets, int> RectBaseT;
+typedef class RectBase<Rect, Point, Size, Insets, Vector2d, int> RectBaseT;
 
 Rect::Rect() : RectBaseT(gfx::Point()) {
 }
 
 Rect::Rect(int width, int height)
     : RectBaseT(gfx::Size(width, height)) {
 }
 
 Rect::Rect(int x, int y, int width, int height)
     : RectBaseT(gfx::Point(x, y), gfx::Size(width, height)) {
@@ skipping 67 matching lines @@
   return result;
 }
 
 Rect SubtractRects(const Rect& a, const Rect& b) {
   Rect result = a;
   result.Subtract(b);
   return result;
 }
 
 }  // namespace gfx