Add more components to "gn check", work on dom_distiller.

components/proxy_config/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.
 
 # GYP version: components/proxy_config.gypi:proxy_config
 component("proxy_config") {
   sources = [
     "pref_proxy_config_tracker.cc",
     "pref_proxy_config_tracker.h",
     "pref_proxy_config_tracker_impl.cc",
@@ skipping 10 matching lines @@
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 
   defines = [ "PROXY_CONFIG_IMPLEMENTATION" ]
 
   deps = [
     "//base",
     "//base:prefs",
     "//net",
     "//url",
   ]
+
+  # TODO(https://crbug.com/562773): Break a header include cycle on ChromeOS
+  # and disable include checking so GN doesn't complain about the missing
+  # dependency (it still links OK). This cycle should be fixed and header
+  # checking enabled.
+  if (is_chromeos) {
+    check_includes = false
+  } else {
+    deps += [ "//components/pref_registry" ]
+  }
 }
 
 source_set("unit_tests") {
   testonly = true
   sources = [
     "pref_proxy_config_tracker_impl_unittest.cc",
     "proxy_config_dictionary_unittest.cc",
     "proxy_prefs_unittest.cc",
   ]
   deps = [
     ":proxy_config",
+    "//base",
+    "//base:prefs_test_support",
+    "//base/test:test_support",
+    "//net",
     "//testing/gmock",
     "//testing/gtest",
   ]
 }