Revert of Deletes mojo::Callback

components/font_service/BUILD.gn

 # Copyright 2015 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")
 import("//mojo/public/mojo_application_manifest.gni")
 
 source_set("lib") {
   sources = [
     "font_service_app.cc",
@@ skipping 16 matching lines @@
 }
 
 mojo_native_application("font_service") {
   sources = [
     "main.cc",
   ]
 
   deps = [
     ":lib",
     "//base",
-    "//mojo/public/c/system",
+    "//mojo/common",
+    "//mojo/common:common_base",
+    "//mojo/public/cpp/bindings:callback",
     "//services/shell/public/cpp",
   ]
 
   data_deps = [
     ":manifest",
   ]
 }
 
 mojo_application_manifest("manifest") {
   application_name = "font_service"
   source = "manifest.json"
 }