Use a bezier timing function for the overview mode animation

ui/gfx/geometry/cubic_bezier.h

Index: ui/gfx/geometry/cubic_bezier.h
diff --git a/ui/gfx/geometry/cubic_bezier.h b/ui/gfx/geometry/cubic_bezier.h
new file mode 100644
index 0000000000000000000000000000000000000000..645dfb7106de68d0cf001a4175cb364c45b409b5
--- /dev/null
+++ b/ui/gfx/geometry/cubic_bezier.h
@@ -0,0 +1,36 @@
+// Copyright 2014 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_GFX_GEOMETRY_CUBIC_BEZIER_H_
+#define UI_GFX_GEOMETRY_CUBIC_BEZIER_H_
+
+#include "base/macros.h"
+#include "ui/gfx/gfx_export.h"
+
+namespace gfx {
+
+class GFX_EXPORT CubicBezier {
+ public:
+  CubicBezier(double x1, double y1, double x2, double y2);
+  ~CubicBezier();
+
+  // Returns an approximation of y at the given x.
+  double Solve(double x) const;
+
+  // Sets |min| and |max| to the bezier's minimum and maximium y values in the
+  // interval [0, 1].
+  void Range(double* min, double* max) const;
+
+ private:
+  double x1_;
+  double y1_;
+  double x2_;
+  double y2_;
+
+  DISALLOW_ASSIGN(CubicBezier);
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_GEOMETRY_CUBIC_BEZIER_H_