Enable the ManagedBookmarks policy on all platforms.

chrome/browser/bookmarks/bookmark_model_factory.cc

 // 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.
 
 #include "chrome/browser/bookmarks/bookmark_model_factory.h"
 
 #include "base/command_line.h"
 #include "base/deferred_sequenced_task_runner.h"
 #include "base/memory/singleton.h"
 #include "base/prefs/pref_service.h"
@@ skipping 70 matching lines @@
 
 void BookmarkModelFactory::RegisterProfilePrefs(
     user_prefs::PrefRegistrySyncable* registry) {
   // Don't sync this, as otherwise, due to a limitation in sync, it
   // will cause a deadlock (see http://crbug.com/97955).  If we truly
   // want to sync the expanded state of folders, it should be part of
   // bookmark sync itself (i.e., a property of the sync folder nodes).
   registry->RegisterListPref(prefs::kBookmarkEditorExpandedNodes,
                              new base::ListValue,
                              user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
+  registry->RegisterListPref(
+      prefs::kManagedBookmarks,
+      user_prefs::PrefRegistrySyncable::UNSYNCABLE_PREF);
 }
 
 content::BrowserContext* BookmarkModelFactory::GetBrowserContextToUse(
     content::BrowserContext* context) const {
   return chrome::GetBrowserContextRedirectedInIncognito(context);
 }
 
 bool BookmarkModelFactory::ServiceIsNULLWhileTesting() const {
   return true;
 }