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

chrome/chrome_browser.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.
 
 {
   'targets': [
     {
       'target_name': 'browser',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 1199 matching lines @@
         'browser/extensions/extension_proxy_api_helpers.h',
         'browser/extensions/extension_scoped_prefs.h',
         'browser/extensions/extension_service.cc',
         'browser/extensions/extension_service.h',
         'browser/extensions/extension_sorting.cc',
         'browser/extensions/extension_sorting.h',
         'browser/extensions/extension_special_storage_policy.cc',
         'browser/extensions/extension_special_storage_policy.h',
         'browser/extensions/extension_sync_data.cc',
         'browser/extensions/extension_sync_data.h',
+        'browser/extensions/extension_system.cc',
+        'browser/extensions/extension_system.h',
+        'browser/extensions/extension_system_factory.cc',
+        'browser/extensions/extension_system_factory.h',
         'browser/extensions/extension_tab_helper.cc',
         'browser/extensions/extension_tab_helper.h',
         'browser/extensions/extension_tab_helper_delegate.cc',
         'browser/extensions/extension_tab_helper_delegate.h',
         'browser/extensions/extension_tab_id_map.cc',
         'browser/extensions/extension_tab_id_map.h',
         'browser/extensions/extension_tab_util.cc',
         'browser/extensions/extension_tab_util.h',
         'browser/extensions/extension_tabs_module.cc',
         'browser/extensions/extension_tabs_module.h',
@@ skipping 4363 matching lines @@
       'type': 'static_library',
       'sources': [ 'browser/history/in_memory_url_index_cache.proto' ],
       'variables': {
         'proto_in_dir': 'browser/history',
         'proto_out_dir': 'chrome/browser/history',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],
 }