[Password Generation] Add FormFieldData.css_classes to mojo

components/autofill/content/public/cpp/autofill_types_struct_traits.h

Index: components/autofill/content/public/cpp/autofill_types_struct_traits.h
diff --git a/components/autofill/content/public/cpp/autofill_types_struct_traits.h b/components/autofill/content/public/cpp/autofill_types_struct_traits.h
index d6651c40d181de8f5c86bd640645f6723af69b4f..e3845a43c8d2d48b18944819b636cb77017072cb 100644
--- a/components/autofill/content/public/cpp/autofill_types_struct_traits.h
+++ b/components/autofill/content/public/cpp/autofill_types_struct_traits.h
@@ -120,6 +120,10 @@ struct StructTraits<autofill::mojom::FormFieldData, autofill::FormFieldData> {
     return r.placeholder;
   }
 
+  static const base::string16& css_classes(const autofill::FormFieldData& r) {
+    return r.css_classes;
+  }
+
   static uint64_t max_length(const autofill::FormFieldData& r) {
     return r.max_length;
   }