Take extensions out of Profile into a profile-keyed service, ExtensionSystem.

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 110 matching lines @@
         'browser/chromeos/login/mock_login_status_consumer.h',
         'browser/chromeos/login/mock_signed_settings_helper.cc',
         'browser/chromeos/login/mock_signed_settings_helper.h',
         # The only thing used from browser is Browser::Type.
         'browser/extensions/mock_extension_special_storage_policy.cc',
         'browser/extensions/mock_extension_special_storage_policy.h',
         'browser/extensions/test_extension_prefs.cc',
         'browser/extensions/test_extension_prefs.h',
         'browser/extensions/test_extension_service.cc',
         'browser/extensions/test_extension_service.h',
+        'browser/extensions/test_extension_system.cc',
+        'browser/extensions/test_extension_system.h',
         'browser/mock_browsing_data_appcache_helper.cc',
         'browser/mock_browsing_data_appcache_helper.h',
         'browser/mock_browsing_data_cookie_helper.cc',
         'browser/mock_browsing_data_cookie_helper.h',
         'browser/mock_browsing_data_database_helper.cc',
         'browser/mock_browsing_data_database_helper.h',
         'browser/mock_browsing_data_file_system_helper.cc',
         'browser/mock_browsing_data_file_system_helper.h',
         'browser/mock_browsing_data_indexed_db_helper.cc',
         'browser/mock_browsing_data_indexed_db_helper.h',
@@ skipping 4535 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'
 }