ui: Add non-member Vector2dScale() and Vector3dScale() methods to create scaled vectors

ui/gfx/vector2d_f.cc

Index: ui/gfx/vector2d_f.cc
diff --git a/ui/gfx/vector2d_f.cc b/ui/gfx/vector2d_f.cc
index 3671c62869c6a7fc3e4c39471b1c71294c5dcf70..f0d28c94335875b0dd1281676546ea03567ebeb1 100644
--- a/ui/gfx/vector2d_f.cc
+++ b/ui/gfx/vector2d_f.cc
@@ -61,4 +61,10 @@ double DotProduct(const Vector2dF& lhs, const Vector2dF& rhs) {
       static_cast<double>(lhs.y()) * rhs.y();
 }
 
+Vector2dF ScaleVector2d(const Vector2dF& v, float x_scale, float y_scale) {
+  Vector2dF scaled_v(v);
+  scaled_v.Scale(x_scale, y_scale);
+  return scaled_v;
+}
+
 }  // namespace gfx