GCAPI should append to the existing experiment_labels instead of clobbering them.

chrome/chrome_installer.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': {
     'lastchange_path': '../build/util/LASTCHANGE',
     'libpeer_target_type%': 'static_library',
     # 'branding_dir' is set in the 'conditions' section at the bottom.
   },
@@ skipping 47 matching lines @@
             'installer_util',
             '../base/base.gyp:base',
             '../base/base.gyp:test_support_base',
             '../testing/gtest.gyp:gtest',
           ],
           'include_dirs': [
             '..',
           ],
           'sources': [
             'installer/gcapi/gcapi_last_run_test.cc',
+            'installer/gcapi/gcapi_omaha_experiment_test.cc',
             'installer/gcapi/gcapi_reactivation_test.cc',
+            'installer/gcapi/gcapi_test_registry_overrider.cc',
+            'installer/gcapi/gcapi_test_registry_overrider.h',
             'installer/gcapi/gcapi_test.cc',
             'installer/gcapi/gcapi_test.rc',
             'installer/gcapi/resource.h',
           ],
         },
         {
           'target_name': 'installer_util_unittests',
           'type': 'executable',
           'dependencies': [
             'installer_util',
@@ skipping 1142 matching lines @@
          'branding_dir_100': 'app/theme/default_100_percent/google_chrome',
       },
     }, { # else branding!="Chrome"
       'variables': {
          'branding_dir': 'app/theme/chromium',
          'branding_dir_100': 'app/theme/default_100_percent/chromium',
       },
     }],
   ],
 }