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

ui/gfx/vector2d.h

Index: ui/gfx/vector2d.h
diff --git a/ui/gfx/vector2d.h b/ui/gfx/vector2d.h
new file mode 100644
index 0000000000000000000000000000000000000000..19b240d8c2f429b06f8f6fc3d779e84445f91146
--- /dev/null
+++ b/ui/gfx/vector2d.h
@@ -0,0 +1,84 @@
+// 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.
+
+// Defines a simple integer vector class.  This class is used to indicate a
+// distance in two dimentions between two points. Subtracting two points should
+// produce a vector, and adding a vector to a point produces the point at the
+// vector's distance from the original point.
+
+#ifndef UI_GFX_VECTOR2D_H_
+#define UI_GFX_VECTOR2D_H_
+
+#include <cmath>
+#include <string>
+
+#include "ui/base/ui_export.h"
+#include "ui/gfx/vector2d_f.h"
+
+namespace gfx {
+
+class UI_EXPORT Vector2d {
+ public:
+  Vector2d();
+  Vector2d(int x, int y);
+
+  int x() const { return x_; }
+  void set_x(int x) { x_ = x; }
+
+  int y() const { return y_; }
+  void set_y(int y) { y_ = y; }
+
+  bool IsZero() const { return x_ == 0 && y_ == 0; }
+
+  void Grow(int x, int y) {
+    x_ += x;
+    y_ += y;
+  }
+
+  void Add(const Vector2d& other) {
+    x_ += other.x_;
+    y_ += other.y_;
+  }
+
+  float LengthSquared() const {
+    return x_ * x_ + y_ * y_;
+  }
+
+  float Length() const {
+    return static_cast<float>(std::sqrt(
+        static_cast<double>(x_) * x_ + static_cast<double>(y_) * y_));
+  }
+
+  std::string ToString() const;
+
+  operator Vector2dF() const { return Vector2dF(x_, y_); }
+
+ private:
+  int x_;
+  int y_;
+};
+
+inline bool operator==(const Vector2d& lhs, const Vector2d& rhs) {
+  return lhs.x() == rhs.x() && lhs.y() == rhs.y();
+}
+
+inline Vector2d operator-(const Vector2d& v) {
+  return Vector2d(-v.x(), -v.y());
+}
+
+inline Vector2d operator+(const Vector2d& lhs, const Vector2d& rhs) {
+  Vector2d result = lhs;
+  result.Add(rhs);
+  return result;
+}
+
+inline Vector2d operator-(const Vector2d& lhs, const Vector2d& rhs) {
+  Vector2d result = lhs;
+  result.Add(-rhs);
+  return result;
+}
+
+}  // namespace gfx
+
+#endif // UI_GFX_VECTOR2D_H_