Add initial components unit tests to GN build.

components/components_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': {
     # This turns on e.g. the filename-based detection of which
     # platforms to include source files on (e.g. files ending in
     # _mac.h or _mac.cc are only compiled on MacOSX).
     'chromium_code': 1,
     'grit_out_dir': '<(SHARED_INTERMEDIATE_DIR)/components',
    },
   'conditions': [
     ['android_webview_build == 0', {
       'targets': [
         {
+          # GN version: //components/components_unittests
           'target_name': 'components_unittests',
           'type': '<(gtest_target_type)',
           'sources': [
+            # Note: sources list duplicated in GN build. In the GN build,
+            # each component has its own unit tests target defined in its
+            # directory that are then linked into the final content_unittests.
             'auto_login_parser/auto_login_parser_unittest.cc',
             'autocomplete/autocomplete_input_unittest.cc',
             'autofill/content/browser/content_autofill_driver_unittest.cc',
             'autofill/content/browser/request_autocomplete_manager_unittest.cc',
             'autofill/content/browser/wallet/full_wallet_unittest.cc',
             'autofill/content/browser/wallet/instrument_unittest.cc',
             'autofill/content/browser/wallet/wallet_address_unittest.cc',
             'autofill/content/browser/wallet/wallet_client_unittest.cc',
             'autofill/content/browser/wallet/wallet_items_unittest.cc',
             'autofill/content/browser/wallet/wallet_service_url_unittest.cc',
@@ skipping 27 matching lines @@
             'autofill/core/browser/phone_number_i18n_unittest.cc',
             'autofill/core/browser/phone_number_unittest.cc',
             'autofill/core/browser/validation_unittest.cc',
             'autofill/core/browser/webdata/autofill_profile_syncable_service_unittest.cc',
             'autofill/core/browser/webdata/autofill_table_unittest.cc',
             'autofill/core/browser/webdata/web_data_service_unittest.cc',
             'autofill/core/common/form_data_unittest.cc',
             'autofill/core/common/form_field_data_unittest.cc',
             'autofill/core/common/password_form_fill_data_unittest.cc',
             'autofill/core/common/save_password_progress_logger_unittest.cc',
+            # Note: GN tests converted to here, need to do the rest.
             'bookmarks/browser/bookmark_codec_unittest.cc',
             'bookmarks/browser/bookmark_expanded_state_tracker_unittest.cc',
             'bookmarks/browser/bookmark_index_unittest.cc',
             'bookmarks/browser/bookmark_model_unittest.cc',
             'bookmarks/browser/bookmark_utils_unittest.cc',
             'breakpad/app/crash_keys_win_unittest.cc',
             'captive_portal/captive_portal_detector_unittest.cc',
             'cloud_devices/common/cloud_devices_urls_unittest.cc',
             'cloud_devices/common/printer_description_unittest.cc',
             'data_reduction_proxy/browser/data_reduction_proxy_auth_request_handler_unittest.cc',
@@ skipping 763 matching lines @@
               'dependencies': [
                 '../base/allocator/allocator.gyp:allocator',
               ],
             }],
           ],
         },
       ],
     }],
   ],
 }