Supporting undoing bookmark deletion without creating new ID.

components/undo.gypi

 # Copyright 2015 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': [
     {
       # GN version: //components/undo
       'target_name': 'undo_component',
       'type': 'static_library',
       'include_dirs': [
         '..',
       ],
       'dependencies': [
         '../base/base.gyp:base',
         '../ui/base/ui_base.gyp:ui_base',
         'bookmarks_browser',
         'components_strings.gyp:components_strings',
         'keyed_service_core',
       ],
       'sources': [
-        'undo/bookmark_renumber_observer.h',
         'undo/bookmark_undo_service.cc',
         'undo/bookmark_undo_service.h',
         'undo/bookmark_undo_utils.cc',
         'undo/bookmark_undo_utils.h',
         'undo/undo_manager.cc',
         'undo/undo_manager.h',
         'undo/undo_manager_observer.h',
         'undo/undo_operation.h',
       ],
     },
   ],
 }