[Ext Registry] Do not try to re-watch registry if we are already watching it.

chrome/test/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/chrome_build.gni")
 import("//build/config/compiler/compiler.gni")
 import("//build/config/crypto.gni")
 import("//build/config/features.gni")
 import("//build/config/ui.gni")
 import("//chrome/common/features.gni")
@@ skipping 4153 matching lines @@
       # This will add all of the unit tests for the schema compiler to this
       # target.
       "//tools/json_schema_compiler/test:unit_tests",
     ]
     if (enable_service_discovery) {
       sources += [
         "../browser/extensions/api/mdns/dns_sd_registry_unittest.cc",
         "../browser/extensions/api/mdns/mdns_api_unittest.cc",
       ]
     }
+    if (is_win) {
+      sources +=
+          [ "../browser/extensions/external_registry_loader_win_unittest.cc" ]
+    }
     if (!is_chromeos) {
       sources += [
         "../browser/extensions/api/messaging/native_message_process_host_unittest.cc",
         "../browser/extensions/api/messaging/native_messaging_host_manifest_unittest.cc",
         "../browser/extensions/api/messaging/native_messaging_policy_handler_unittest.cc",
       ]
     }
     if (enable_media_router) {
       sources += [
         "../browser/media/cast_remoting_sender_unittest.cc",
@@ skipping 1046 matching lines @@
 }
 
 if (is_win) {
   loadable_module("conflicts_dll") {
     testonly = true
     sources = [
       "conflicts/conflicts_dll.cc",
     ]
   }
 }