Create PluginMetricsProvider class.

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 1067 matching lines @@
         'browser/media_galleries/media_galleries_scan_result_dialog_controller_unittest.cc',
         'browser/media_galleries/media_scan_manager_unittest.cc',
         'browser/media_galleries/win/mtp_device_object_enumerator_unittest.cc',
         'browser/metrics/cloned_install_detector_unittest.cc',
         'browser/metrics/compression_utils_unittest.cc',
         'browser/metrics/extension_metrics_unittest.cc',
         'browser/metrics/machine_id_provider_win_unittest.cc',
         'browser/metrics/metrics_log_unittest.cc',
         'browser/metrics/metrics_service_unittest.cc',
         'browser/metrics/metrics_state_manager_unittest.cc',
+        'browser/metrics/plugin_metrics_provider_unittest.cc',

[Ilya Sherman, 2014/05/22 14:52:20]

Should this only be run when plugins are enabled?

[Alexei Svitkine (slow), 2014/05/22 15:38:54]

Indeed. I forgot that this is in a different file, so isn't affected by the
other file's rule. Done now.

         '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',
@@ skipping 1722 matching lines @@
             'unit_tests.isolate',
           ],
           'sources': [
             'unit_tests.isolate',
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }