Fix chrome target in Windows GN build.

components/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/features.gni")
 import("//build/config/ui.gni")
 import("//testing/test.gni")
 
 # Collection of all components. You wouldn't link to this, but this is rather
 # to reference the files so they can be compiled by the build system.
@@ skipping 253 matching lines @@
   # TODO(GYP) need this target.
   #'breakpad/app/crash_keys_win_unittest.cc',
 
   # Precache tests need these defines.
   #configs += [ "//components/precache/core:precache_config" ]
 
   if (toolkit_views) {
     # TODO(GYP) enable this as above.
     #deps += [ "//components/constrained_window:unit_tests" ]
   }
+  if (is_win) {
+    deps += [ "//components/browser_watcher:unit_tests" ]
+  }
 }