Remove GN GYP generator.

base/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.
 
 import("//build/config/ui.gni")
 
 component("base") {
-  external = true
   sources = [
     "../build/build_config.h",
     "third_party/dmg_fp/dmg_fp.h",
     "third_party/dmg_fp/g_fmt.cc",
     "third_party/dmg_fp/dtoa_wrapper.cc",
     "third_party/icu/icu_utf.cc",
     "third_party/icu/icu_utf.h",
     "allocator/allocator_extension.cc",
     "allocator/allocator_extension.h",
     "allocator/type_profiler_control.cc",
@@ skipping 817 matching lines @@
       "message_loop/message_pump_gtk.cc",
       "message_loop/message_pump_gtk.h",
     ]
   }
 }
 
 # This is the subset of files from base that should not be used with a dynamic
 # library. Note that this library cannot depend on base because base depends on
 # base_static.
 static_library("base_static") {
-  external = true
   sources = [
     "base_switches.cc",
     "base_switches.h",
     "win/pe_image.cc",
     "win/pe_image.h",
   ]
 }
 
 component("base_i18n") {
-  external = true
   sources = [
     "i18n/base_i18n_export.h",
     "i18n/bidi_line_iterator.cc",
     "i18n/bidi_line_iterator.h",
     "i18n/break_iterator.cc",
     "i18n/break_iterator.h",
     "i18n/char_iterator.cc",
     "i18n/char_iterator.h",
     "i18n/case_conversion.cc",
     "i18n/case_conversion.h",
@@ skipping 35 matching lines @@
   #    # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
   #    'msvs_disabled_warnings': [
   #      4267,
   #    ],
   #  }],
   #],
   #'variables': {
   #  'optimize': 'max',
   #},
 }