Enable use_once_callback on mojom GN rule by default

mojo/public/interfaces/bindings/tests/BUILD.gn

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("../../../tools/bindings/mojom.gni")
 
 group("tests") {
   testonly = true
   deps = [
     ":test_interfaces",
@@ skipping 51 matching lines @@
     "test_structs.mojom",
     "test_sync_methods.mojom",
     "test_unions.mojom",
     "validation_test_interfaces.mojom",
   ]
   public_deps = [
     ":echo",
     ":test_mojom_import",
     ":test_mojom_import2",
   ]
+
+  # TODO(crbug.com/714018): Convert the implementation to use OnceCallback.
+  use_once_callback = false
 }
 
 component("test_export_component") {
   testonly = true
   deps = [
     ":test_export",
   ]
 }
 
 if (!is_ios) {
@@ skipping 97 matching lines @@
     ":test_mojom_import",
     ":test_mojom_import_wrapper_wrapper",
   ]
 }
 
 mojom("test_struct_traits_interfaces") {
   testonly = true
   sources = [
     "struct_with_traits.mojom",
   ]
+
+  # TODO(crbug.com/714018): Convert the implementation to use OnceCallback.
+  use_once_callback = false
 }
 
 mojom("test_associated_interfaces") {
   # These files are not included in the test_interfaces target because
   # associated interfaces are not supported by all bindings languages yet.
   testonly = true
   sources = [
     "test_associated_interfaces.mojom",
     "validation_test_associated_interfaces.mojom",
   ]
 
   public_deps = [
     ":test_interfaces",
   ]
+
+  # TODO(crbug.com/714018): Convert the implementation to use OnceCallback.
+  use_once_callback = false
 }
 
 mojom("versioning_test_service_interfaces") {
   testonly = true
   sources = [
     "versioning_test_service.mojom",
   ]
 }
 
 mojom("versioning_test_client_interfaces") {
   testonly = true
   sources = [
     "versioning_test_client.mojom",
   ]
 }
 
 mojom("test_wtf_types") {
   testonly = true
 
   sources = [
     "test_wtf_types.mojom",
   ]
+
+  # TODO(crbug.com/714018): Convert the implementation to use OnceCallback.
+  use_once_callback = false
 }
 
 mojom("test_no_sources") {
   testonly = true
 
   public_deps = [
     ":test_interfaces",
   ]
 }
 
 mojom("echo") {
   testonly = true
   sources = [
     "echo.mojom",
     "echo_import.mojom",
   ]
   use_new_js_bindings = true
 }