Add chrome, installer_util targets to GN build.

chrome/chrome_installer_util.gypi

 # Copyright (c) 2012 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.
 
 {
   'target_defaults': {
     'variables': {
       'installer_util_target': 0,
     },
     'target_conditions': [
@@ skipping 191 matching lines @@
             'Common_Base': {
               'msvs_target_platform': 'x64',
             },
           },
         },
       ],
     }],
     ['OS!="win"', {
       'targets': [
         {
+          # GN version: //chrome/installer/util
           'target_name': 'installer_util',
           'type': 'static_library',
           'dependencies': [
             '<(DEPTH)/base/base.gyp:base',
             '<(DEPTH)/chrome/chrome_resources.gyp:chrome_resources',
             '<(DEPTH)/chrome/chrome_resources.gyp:chrome_strings',
           ],
           'sources': [
+            # Note: sources list duplicated in GN build.
             'installer/util/google_update_experiment_util.cc',
             'installer/util/google_update_experiment_util.h',
             'installer/util/master_preferences.cc',
             'installer/util/master_preferences.h',
             'installer/util/master_preferences_constants.cc',
             'installer/util/master_preferences_constants.h',
           ],
           'include_dirs': [
             '<(DEPTH)',
           ],
         }
       ],
     }],
 
   ],
 }