Explicit animation support

ui/base/animation/tween.cc

Index: ui/base/animation/tween.cc
diff --git a/ui/base/animation/tween.cc b/ui/base/animation/tween.cc
index 515ae576ed5c20189c4be94d40b47ea49ad293cc..a16bb1862e79983f667410741babd7bd5758b9c1 100644
--- a/ui/base/animation/tween.cc
+++ b/ui/base/animation/tween.cc
@@ -11,7 +11,10 @@
 #endif
 
 #include "base/logging.h"
-#include "ui/gfx/rect.h"
+
+#if !defined(OS_MACOSX)
+#include "ui/gfx/interpolated_transform.h"
+#endif
 
 namespace ui {
 
@@ -83,4 +86,42 @@ gfx::Rect Tween::ValueBetween(double value,
                                 target_bounds.height()));
 }
 
+#if !defined(OS_MACOSX)
+// static
+Transform Tween::ValueBetween(double value,
+                              const Transform& start_transform,
+                              const Transform& end_transform) {
+  Transform to_return;
+  gfx::Point start_translation, end_translation;
+  float start_rotation, end_rotation;
+  gfx::Point3f start_scale, end_scale;
+  if (InterpolatedTransform::FactorTRS(start_transform,
+                                       &start_translation,
+                                       &start_rotation,
+                                       &start_scale) &&
+      InterpolatedTransform::FactorTRS(end_transform,
+                                       &end_translation,
+                                       &end_rotation,
+                                       &end_scale)) {
+    to_return.SetScale(ValueBetween(value, start_scale.x(), end_scale.x()),
+                       ValueBetween(value, start_scale.y(), end_scale.y()));
+    to_return.ConcatRotate(ValueBetween(value, start_rotation, end_rotation));
+    to_return.ConcatTranslate(
+        ValueBetween(value, start_translation.x(), end_translation.x()),
+        ValueBetween(value, start_translation.y(), end_translation.y()));
+  } else {
+    for (int row = 0; row < 4; ++row) {
+      for (int col = 0; col < 4; ++col) {
+        to_return.matrix().set(row, col,
+            ValueBetween(value,
+                         start_transform.matrix().get(row, col),
+                         end_transform.matrix().get(row, col)));
+      }
+    }
+  }
+
+  return to_return;
+}
+#endif
+
 }  // namespace ui