Parse /etc/lsb-release only once on ChromeOS

chrome/chrome_tests_unit.gypi

 # Copyright 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.
 {
   'targets': [
     {
       # This target contains mocks and test utilities that don't belong in
       # production libraries but are used by more than one test executable.
       'target_name': 'test_support_common',
       'type': 'static_library',
@@ skipping 698 matching lines @@
         'browser/chromeos/session_length_limiter_unittest.cc',
         'browser/chromeos/proxy_config_service_impl_unittest.cc',
         'browser/chromeos/settings/cros_settings_unittest.cc',
         'browser/chromeos/settings/device_oauth2_token_service_unittest.cc',
         'browser/chromeos/settings/device_settings_provider_unittest.cc',
         'browser/chromeos/settings/device_settings_service_unittest.cc',
         'browser/chromeos/settings/owner_key_util_unittest.cc',
         'browser/chromeos/settings/session_manager_operation_unittest.cc',
         'browser/chromeos/settings/stub_cros_settings_provider_unittest.cc',
         'browser/chromeos/system/automatic_reboot_manager_unittest.cc',
-        'browser/chromeos/system_logs/lsb_release_log_source_unittest.cc',
         'browser/chromeos/version_loader_unittest.cc',
         'browser/command_updater_unittest.cc',
         'browser/component_updater/test/component_installers_unittest.cc',
         'browser/component_updater/test/component_patcher_mock.h',
         'browser/component_updater/test/component_patcher_unittest.cc',
         'browser/component_updater/test/component_updater_service_unittest.cc',
         'browser/component_updater/test/test_installer.cc',
         'browser/component_updater/test/url_request_post_interceptor.cc',
         'browser/content_settings/content_settings_default_provider_unittest.cc',
         'browser/content_settings/content_settings_mock_observer.cc',
@@ skipping 2095 matching lines @@
             'browser_ui',
           ],
           'sources': [
             'browser/ui/app_list/test/fast_show_pickler_unittest.cc',
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }