Adds function to invert a transform to ui::Transform

ui/gfx/transform.cc

Index: ui/gfx/transform.cc
diff --git a/ui/gfx/transform.cc b/ui/gfx/transform.cc
index 53981450964b38141f29b06aabc1747ec4147189..3f0b8ea6f3772ac6e04bfad9ffccccc0d1714e3e 100644
--- a/ui/gfx/transform.cc
+++ b/ui/gfx/transform.cc
@@ -102,6 +102,10 @@ bool Transform::HasChange() const {
   return !matrix_.isIdentity();
 }
 
+bool Transform::GetInverse(Transform* transform) const {
+  return matrix_.invert(&transform->matrix_);
+}
+
 void Transform::TransformPoint(gfx::Point& point) const {
   TransformPointInternal(matrix_, point);
 }