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

services/window_manager/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("//build/config/ui.gni")
 import("//mojo/public/mojo_application.gni")
 import("//testing/test.gni")
 
 mojo_native_application("window_manager") {
   sources = [
@@ skipping 104 matching lines @@
     "//base",
     "//mojo/application",
     "//mojo/application:test_support",
     "//mojo/environment:chromium",
     "//mojo/public/c/system:for_shared_library",
     "//mojo/public/cpp/system:system",
     "//mojo/services/view_manager/public/cpp",
     "//mojo/services/window_manager/public/interfaces",
   ]
 
-  datadeps = [
-    ":window_manager",
-  ]
+  data_deps = [ ":window_manager" ]
 }