Add support for building "ios_chrome_unittests" with gn.

ios/chrome/ios_chrome_tests.gyp

 # 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.
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
+      # GN version: //ios/chrome:ios_chrome_unittests
       'target_name': 'ios_chrome_unittests',
       'type': '<(gtest_target_type)',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../base/base.gyp:base_prefs_test_support',
         '../../base/base.gyp:test_support_base',
         '../../components/components.gyp:bookmarks_test_support',
         '../../components/components.gyp:enhanced_bookmarks_test_support',
         '../../components/components.gyp:favicon_base',
         '../../components/components.gyp:metrics',
@@ skipping 60 matching lines @@
               'test/data/webdata/bookmarkimages',
             ],
             'test_data_prefix': 'ios/chrome',
           },
           'includes': [ '../../build/copy_test_data_ios.gypi' ]
         },
       ],
       'includes': ['ios_chrome_resources_bundle.gypi'],
     },
     {
+      # GN version: //ios/chrome/browser:test_support + //ios/public/test
       'target_name': 'ios_chrome_test_support',
       'type': 'static_library',
       'dependencies': [
         '../../base/base.gyp:base',
         '../../components/components.gyp:password_manager_core_browser_test_support',
         '../../components/components.gyp:signin_ios_browser_test_support',
         '../../testing/gmock.gyp:gmock',
         '../../testing/gtest.gyp:gtest',
         '../../ui/base/ui_base.gyp:ui_base',
         '../../url/url.gyp:url_lib',
@@ skipping 18 matching lines @@
         'test/ios_chrome_scoped_testing_local_state.h',
         'test/ios_chrome_unit_test_suite.cc',
         'test/ios_chrome_unit_test_suite.h',
         'test/run_all_unittests.cc',
         'test/testing_application_context.cc',
         'test/testing_application_context.h',
       ],
     },
   ],
 }