Add common code for extensions event filtering.

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 1792 matching lines @@
         'browser/webdata/web_intents_table_unittest.cc',
         'browser/website_settings_unittest.cc',
         'common/bzip2_unittest.cc',
         'common/child_process_logging_mac_unittest.mm',
         'common/chrome_paths_unittest.cc',
         'common/common_param_traits_unittest.cc',
         'common/content_settings_helper_unittest.cc',
         'common/content_settings_pattern_parser_unittest.cc',
         'common/content_settings_pattern_unittest.cc',
         'common/extensions/csp_validator_unittest.cc',
+        'common/extensions/event_filter_unittest.cc',
         'common/extensions/extension_action_unittest.cc',
         'common/extensions/extension_commands_unittest.cc',
         'common/extensions/extension_constants_unittest.cc',
         'common/extensions/extension_file_util_unittest.cc',
         'common/extensions/extension_icon_set_unittest.cc',
         'common/extensions/extension_l10n_util_unittest.cc',
         'common/extensions/extension_localization_peer_unittest.cc',
         'common/extensions/extension_message_bundle_unittest.cc',
         'common/extensions/extension_permission_set_unittest.cc',
         'common/extensions/extension_resource_unittest.cc',
@@ skipping 2797 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'
 }