mojo_application.gni - data deps are called data_deps these days.

services/dart/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("//mojo/public/mojo_application.gni")
 
 group("dart") {
   deps = [
     ":dart_content_handler",
   ]
@@ skipping 134 matching lines @@
 
   deps = [
     "//base",
     "//mojo/application",
     "//mojo/application:test_support",
     "//mojo/public/cpp/bindings",
     "//mojo/public/cpp/system",
     "//services/dart/test:echo_service_interface",
     "//services/dart/test:pingpong_service_interface",
   ]
-  datadeps = [
+  data_deps = [
     "//services/dart/test/echo",
     "//services/dart/test/pingpong",
     "//services/dart/test/pingpong_target",
   ]
 }