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

ui/gfx/point.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/point.h"
 
 #if defined(OS_WIN)
 #include <windows.h>
 #endif
 
 #include "base/stringprintf.h"
 
 namespace gfx {
 
-template class PointBase<Point, int>;
+template class PointBase<Point, int, Vector2d>;
 
-Point::Point() : PointBase<Point, int>(0, 0) {
+Point::Point() : PointBase<Point, int, Vector2d>(0, 0) {
 }
 
-Point::Point(int x, int y) : PointBase<Point, int>(x, y) {
+Point::Point(int x, int y) : PointBase<Point, int, Vector2d>(x, y) {
 }
 
 #if defined(OS_WIN)
-Point::Point(DWORD point) : PointBase<Point, int>(0, 0){
+Point::Point(DWORD point) : PointBase<Point, int, Vector2d>(0, 0){
   POINTS points = MAKEPOINTS(point);
   set_x(points.x);
   set_y(points.y);
 }
 
-Point::Point(const POINT& point) : PointBase<Point, int>(point.x, point.y) {
+Point::Point(const POINT& point)
+    : PointBase<Point, int, Vector2d>(point.x, point.y) {
 }
 
 Point& Point::operator=(const POINT& point) {
   set_x(point.x);
   set_y(point.y);
   return *this;
 }
 
 POINT Point::ToPOINT() const {
   POINT p;
   p.x = x();
   p.y = y();
   return p;
 }
 #elif defined(OS_MACOSX)
-Point::Point(const CGPoint& point) : PointBase<Point, int>(point.x, point.y) {
+Point::Point(const CGPoint& point)
+    : PointBase<Point, int, Vector2d>(point.x, point.y) {
 }
 
 CGPoint Point::ToCGPoint() const {
   return CGPointMake(x(), y());
 }
 #endif
 
 std::string Point::ToString() const {
   return base::StringPrintf("%d,%d", x(), y());
 }
 
 }  // namespace gfx