Add support for bounds animations

ui/gfx/animation/tween.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 UI_GFX_ANIMATION_TWEEN_H_
 #define UI_GFX_ANIMATION_TWEEN_H_
 
 #include "base/macros.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/animation/animation_export.h"
 #include "ui/gfx/geometry/rect.h"
+#include "ui/gfx/geometry/size_f.h"
 #include "ui/gfx/transform.h"
 
 namespace base {
 class TimeTicks;
 }
 
 namespace gfx {
 
 class ANIMATION_EXPORT Tween {
  public:
@@ skipping 43 matching lines @@
   // specified by www.w3.org/TR/css3-transitions.
   static int LinearIntValueBetween(double value, int start, int target);
   static gfx::Rect RectValueBetween(double value,
                                     const gfx::Rect& start_bounds,
                                     const gfx::Rect& target_bounds);
   static gfx::Transform TransformValueBetween(
       double value,
       const gfx::Transform& start_transform,
       const gfx::Transform& target_transform);
 
+  static gfx::SizeF SizeValueBetween(double value,
+                                     const gfx::SizeF& start_size,
+                                     const gfx::SizeF& target_size);
+
  private:
   Tween();
   ~Tween();
 
   DISALLOW_COPY_AND_ASSIGN(Tween);
 };
 
 }  // namespace gfx
 
 #endif  // UI_GFX_ANIMATION_TWEEN_H_