Add BackgroundModeOptimizer that can restart the browser

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.
 {
   'variables': {
     'chrome_unit_tests_sources': [
       # histograms.xml is analyzed by AboutFlagsHistogramTest, so this
       # dependency is needed to make commit bots run unit_tests on
       # histograms.xml changes.
       '../tools/metrics/histograms/histograms.xml',
@@ skipping 376 matching lines @@
       'renderer/spellchecker/spellcheck_provider_test.cc',
       'renderer/spellchecker/spellcheck_provider_test.h',
       'renderer/spellchecker/spellcheck_unittest.cc',
       'renderer/spellchecker/spellcheck_worditerator_unittest.cc',
       'tools/convert_dict/convert_dict_unittest.cc',
     ],
     'chrome_unit_tests_background_sources': [
       'browser/background/background_application_list_model_unittest.cc',
       'browser/background/background_contents_service_unittest.cc',
       'browser/background/background_mode_manager_unittest.cc',
+      'browser/background/background_mode_optimizer_unittest.cc',
     ],
     'chrome_unit_tests_extensions_sources': [
       '../apps/saved_files_service_unittest.cc',
       '../components/drive/drive_api_util_unittest.cc',
       '../components/drive/drive_app_registry_unittest.cc',
       '../components/drive/drive_uploader_unittest.cc',
       '../components/drive/event_logger_unittest.cc',
       '../components/drive/service/drive_api_service_unittest.cc',
       '../components/drive/service/fake_drive_service_unittest.cc',
       '../tools/json_schema_compiler/test/features_generation_unittest.cc',
@@ skipping 2619 matching lines @@
               'dependencies': [
                 '../tools/xdisplaycheck/xdisplaycheck.gyp:xdisplaycheck',
               ],
             }],
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }