Make gn check //{,mojo}/services/* pass

services/http_server/public/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/tools/bindings/mojom.gni")
 
 mojom("public") {
   sources = [
     "http_request.mojom",
     "http_response.mojom",
     "http_server.mojom",
   ]
 }
 
 source_set("util") {
   sources = [
     "http_server_util.cc",
     "http_server_util.h",
   ]
 
   deps = [
     ":public",
+    "//base",
+    "//mojo/public/cpp/system",
   ]
 }