Add and implement API to associate Google experiment IDs with FieldTrials.

chrome/chrome_tests.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.
 {
   'variables' : {
     'pyautolib_sources': [
       'app/chrome_command_ids.h',
       'app/chrome_dll_resource.h',
       'common/automation_constants.h',
       'common/pref_names.cc',
@@ skipping 2017 matching lines @@
         'common/json_pref_store_unittest.cc',
         'common/json_schema_validator_unittest.cc',
         'common/json_schema_validator_unittest_base.cc',
         'common/json_schema_validator_unittest_base.h',
         'common/json_value_serializer_unittest.cc',
         'common/mac/cfbundle_blocker_unittest.mm',
         'common/mac/mock_launchd.cc',
         'common/mac/mock_launchd.h',
         'common/mac/objc_method_swizzle_unittest.mm',
         'common/mac/objc_zombie_unittest.mm',
+        'common/metrics/experiments_helper_unittest.cc',
         'common/metrics/metrics_log_base_unittest.cc',
         'common/metrics/metrics_log_manager_unittest.cc',
         'common/multi_process_lock_unittest.cc',
         'common/net/gaia/gaia_auth_fetcher_unittest.cc',
         'common/net/gaia/gaia_authenticator_unittest.cc',
         'common/net/gaia/gaia_oauth_client_unittest.cc',
         'common/net/gaia/google_service_auth_error_unittest.cc',
         'common/net/gaia/oauth_request_signer_unittest.cc',
         'common/net/gaia/oauth2_access_token_fetcher_unittest.cc',
         'common/net/gaia/oauth2_api_call_flow_unittest.cc',
@@ skipping 2628 matching lines @@
               # Use outputs of this action as inputs for the main target build.
               # Seems as a misnomer but makes this happy on Linux (scons).
               'process_outputs_as_sources': 1,
             },
           ],  # 'actions'
         },
       ]
     }],  # 'coverage!=0'
   ],  # 'conditions'
 }