Add header files that were missing from BUILD.gn.

ios/chrome/browser/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("//build/config/features.gni")
 import("//third_party/protobuf/proto_library.gni")
 
 declare_args() {
   google_test_gaia_client_id = ""
   google_test_gaia_client_secret = ""
@@ skipping 113 matching lines @@
   deps = [
     ":about_flags",
     ":browser",
     "//base",
     "//components/component_updater",
     "//components/content_settings/core/browser",
     "//components/content_settings/core/common",
     "//components/flags_ui",
     "//components/gcm_driver",
     "//components/history/core/browser",
+    "//components/keyed_service/core",
     "//components/language_usage_metrics",
     "//components/metrics:profiler_ios",
     "//components/metrics_services_manager",
     "//components/net_log",
     "//components/network_time",
     "//components/open_from_clipboard",
     "//components/physical_web/data_source",
     "//components/prefs",
     "//components/rappor",
     "//components/task_scheduler_util",
@@ skipping 86 matching lines @@
     "//components/proxy_config",
     "//components/ssl_config",
     "//components/variations",
     "//ios/web:test_support",
     "//net",
     "//net:test_support",
     "//testing/gtest",
     "//url",
   ]
 }