Explicit animation support

ui/base/animation/tween.h

Index: ui/base/animation/tween.h
diff --git a/ui/base/animation/tween.h b/ui/base/animation/tween.h
index 6bde5dda89abdc2ca934cf02dad863063a3aa72d..02c08c5adf52c23e0b26277e6d478b9b18b34d3b 100644
--- a/ui/base/animation/tween.h
+++ b/ui/base/animation/tween.h
@@ -8,10 +8,11 @@
 
 #include "base/basictypes.h"
 #include "ui/base/ui_export.h"
+#include "ui/gfx/rect.h"
 
-namespace gfx {
-class Rect;
-}
+#if !defined(OS_MACOSX)
+#include "ui/gfx/transform.h"
+#endif
 
 namespace ui {
 
@@ -36,6 +37,11 @@ class UI_EXPORT Tween {
   static gfx::Rect ValueBetween(double value,
                                 const gfx::Rect& start_bounds,
                                 const gfx::Rect& target_bounds);
+#if !defined(OS_MACOSX)
+  static Transform ValueBetween(double value,
+                                const Transform& start_transform,
+                                const Transform& target_transform);
+#endif
 
  private:
   Tween();