Add new ExtensionManagement preference

chrome/chrome_browser_extensions.gypi

 # Copyright (c) 2013 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_browser_extensions_chromeos_sources': [
       'browser/extensions/api/diagnostics/diagnostics_api.cc',
       'browser/extensions/api/diagnostics/diagnostics_api.h',
       'browser/extensions/api/diagnostics/diagnostics_api_chromeos.cc',
@@ skipping 617 matching lines @@
       'browser/extensions/extension_install_prompt_experiment.cc',
       'browser/extensions/extension_install_prompt_experiment.h',
       'browser/extensions/extension_install_ui.cc',
       'browser/extensions/extension_install_ui.h',
       'browser/extensions/extension_install_ui_util.cc',
       'browser/extensions/extension_install_ui_util.h',
       'browser/extensions/extension_keybinding_registry.cc',
       'browser/extensions/extension_keybinding_registry.h',
       'browser/extensions/extension_management.cc',
       'browser/extensions/extension_management.h',
+      'browser/extensions/extension_management_constants.cc',
+      'browser/extensions/extension_management_constants.h',
       'browser/extensions/extension_message_bubble_controller.cc',
       'browser/extensions/extension_message_bubble_controller.h',
       'browser/extensions/extension_renderer_state.cc',
       'browser/extensions/extension_renderer_state.h',
       'browser/extensions/extension_resource_protocols.cc',
       'browser/extensions/extension_resource_protocols.h',
       'browser/extensions/extension_service.cc',
       'browser/extensions/extension_service.h',
       'browser/extensions/extension_special_storage_policy.cc',
       'browser/extensions/extension_special_storage_policy.h',
@@ skipping 452 matching lines @@
           ],
         }, {  # use_brlapi==0
           'sources': [
             'browser/extensions/api/braille_display_private/braille_controller_stub.cc',
           ],
         }],
       ],
     },
   ],
 }