Enable use_once_callback on mojom GN rule by default

chrome/common/media_router/mojo/BUILD.gn

 # Copyright 2017 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("//mojo/public/tools/bindings/mojom.gni")
 
 mojom("dial_utility_interfaces") {
   sources = [
     "dial_device_description_parser.mojom",
   ]
 
   public_deps = [
     "//mojo/common:common_custom_types",
   ]
+
+  # TODO(crbug.com/714018): Convert the implementation to use OnceCallback.
+  use_once_callback = false
 }
 
 mojom("media_controller") {
   sources = [
     "media_controller.mojom",
     "media_status.mojom",
   ]
 
   public_deps = [
     "//mojo/common:common_custom_types",
   ]
 }
 
 mojom("media_router") {
   sources = [
     "media_router.mojom",
   ]
 
   public_deps = [
     ":media_controller",
     "//mojo/common:common_custom_types",
     "//net/interfaces:interfaces",
     "//url/mojo:url_mojom_gurl",
     "//url/mojo:url_mojom_origin",
   ]
+
+  # TODO(crbug.com/714018): Convert the implementation to use OnceCallback.
+  use_once_callback = false
 }
 
 mojom("media_router_test_interfaces") {
   sources = [
     "media_router_traits_test_service.mojom",
   ]
 
   public_deps = [
     ":media_router",
   ]
+
+  # TODO(crbug.com/714018): Convert the implementation to use OnceCallback.
+  use_once_callback = false
 }