[Variations] Bring variations_http_header_provider to variations component

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 1088 matching lines @@
         'browser/metrics/chrome_metrics_service_accessor_unittest.cc',
         'browser/metrics/cloned_install_detector_unittest.cc',
         'browser/metrics/extensions_metrics_provider_unittest.cc',
         'browser/metrics/gpu_metrics_provider_unittest.cc',
         'browser/metrics/plugin_metrics_provider_unittest.cc',
         'browser/metrics/profiler_metrics_provider_unittest.cc',
         'browser/metrics/rappor/sampling_unittest.cc',
         'browser/metrics/thread_watcher_unittest.cc',
         'browser/metrics/thread_watcher_android_unittest.cc',
         'browser/metrics/time_ticks_experiment_unittest.cc',
-        'browser/metrics/variations/variations_http_header_provider_unittest.cc',
         'browser/metrics/variations/variations_request_scheduler_mobile_unittest.cc',
         'browser/metrics/variations/variations_request_scheduler_unittest.cc',
         'browser/metrics/variations/variations_seed_store_unittest.cc',
         'browser/metrics/variations/variations_service_unittest.cc',
         'browser/net/chrome_fraudulent_certificate_reporter_unittest.cc',
         'browser/net/chrome_network_delegate_unittest.cc',
         'browser/net/client_hints_unittest.cc',
         'browser/net/connection_tester_unittest.cc',
         'browser/net/dns_probe_runner_unittest.cc',
         'browser/net/dns_probe_service_unittest.cc',
@@ skipping 1786 matching lines @@
             'unit_tests.isolate',
           ],
           'sources': [
             'unit_tests.isolate',
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }