Add the basic code skeleton for system info event router

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 2829 matching lines @@
         'browser/extensions/extension_tabs_apitest.cc',
         'browser/extensions/extension_test_message_listener.cc',
         'browser/extensions/extension_test_message_listener.h',
         'browser/extensions/extension_toolbar_model_browsertest.cc',
         'browser/extensions/extension_url_rewrite_browsertest.cc',
         'browser/extensions/extension_websocket_apitest.cc',
         'browser/extensions/gpu_browsertest.cc',
         'browser/extensions/isolated_app_browsertest.cc',
         'browser/extensions/lazy_background_page_apitest.cc',
         'browser/extensions/lazy_background_page_test_util.h',
+        'browser/extensions/mock_system_info_watcher.cc',
+        'browser/extensions/mock_system_info_watcher.h',
         'browser/extensions/mutation_observers_apitest.cc',
         'browser/extensions/notifications_apitest.cc',
         'browser/extensions/options_page_apitest.cc',
         'browser/extensions/page_action_browsertest.cc',
         'browser/extensions/platform_app_browsertest.cc',
         'browser/extensions/platform_app_browsertest_util.cc',
         'browser/extensions/platform_app_browsertest_util.h',
         'browser/extensions/plugin_apitest.cc',
         'browser/extensions/process_management_browsertest.cc',
         'browser/extensions/sandboxed_pages_apitest.cc',
@@ skipping 1835 matching lines @@
                 '--result', '<@(_outputs)',
                 '--isolate', 'browser_tests.isolate',
               ],
             },
           ],
         },
       ],
     }],
   ],  # 'conditions'
 }