Remove GN GYP generator.

url/BUILD.gn

 # Copyright (c) 2013 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.
 
 component("url") {
-  external = true
   if (is_win) {
     # Don't conflict with Windows' "url.dll".
     output_name = "url_lib"
   }
   sources = [
     "gurl.cc",
     "gurl.h",
     "third_party/mozilla/url_parse.cc",
     "third_party/mozilla/url_parse.h",
     "url_canon.h",
@@ skipping 33 matching lines @@
 
   deps = [
     "//base",
     "//third_party/icu:icudata",
     "//third_party/icu:icui18n",
     "//third_party/icu:icuuc",
   ]
 }
 
 test("url_unittests") {
-  external = true
   sources = [
     "gurl_unittest.cc",
     "url_canon_unittest.cc",
     "url_parse_unittest.cc",
     "url_test_utils.h",
     "url_util_unittest.cc",
   ]
 
   #if (is_posix && !is_mac && !is_ios) {
   #  # TODO(dmikurube): Kill linux_use_tcmalloc. http://crbug.com/345554
   #  if ((use_allocator!="none" && use_allocator!="see_use_tcmalloc") || (use_allocator=="see_use_tcmalloc" && linux_use_tcmalloc) {
   #    deps += "//base/allocator"
   #  }
   #}
 
   # if (is_win) {
   #   TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   #   'msvs_disabled_warnings': [ 4267, ]
   # }
 
   deps = [
     ":url",
     "//base:base_i18n",
     "//base/test:run_all_unittests",
     "//testing/gtest",
     "//third_party/icu:icuuc",
   ]
 }