ui: Prefer +/- operators to apply offsets.

ui/gfx/vector3d_f.h

Index: ui/gfx/vector3d_f.h
diff --git a/ui/gfx/vector3d_f.h b/ui/gfx/vector3d_f.h
index a2845f89267880e28b4634df450471e30c520402..ccd84ec53b01c5a283df0a99907581b40b83b108 100644
--- a/ui/gfx/vector3d_f.h
+++ b/ui/gfx/vector3d_f.h
@@ -95,6 +95,17 @@ inline Vector3dF CrossProduct(const Vector3dF& lhs, const Vector3dF& rhs) {
 // Return the dot product of two vectors.
 UI_EXPORT float DotProduct(const Vector3dF& lhs, const Vector3dF& rhs);
 
+// Return a vector that is |v| scaled by the given scale factors along each
+// axis.
+UI_EXPORT Vector3dF ScaleVector3d(const Vector3dF& v,
+                                  float x_scale,
+                                  float y_scale,
+                                  float z_scale);
+
+// Return a vector that is |v| scaled by the given scale factor.
+inline Vector3dF ScaleVector3d(const Vector3dF& v, float scale) {
+  return ScaleVector3d(v, scale, scale, scale);
+}
 
 }  // namespace gfx