Add a SigninAllowed policy.

chrome/browser/profiles/profile_impl.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/profiles/profile_impl.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/command_line.h"
 #include "base/compiler_specific.h"
@@ skipping 261 matching lines @@
 const char* const ProfileImpl::kPrefExitTypeNormal = "Normal";
 
 // static
 void ProfileImpl::RegisterUserPrefs(PrefRegistrySyncable* registry) {
   registry->RegisterBooleanPref(prefs::kSavingBrowserHistoryDisabled,
                                 false,
                                 PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterBooleanPref(prefs::kAllowDeletingBrowserHistory,
                                 true,
                                 PrefRegistrySyncable::UNSYNCABLE_PREF);
+  registry->RegisterBooleanPref(prefs::kSigninAllowed,
+                                true,
+                                PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterBooleanPref(prefs::kForceSafeSearch,
                                 false,
                                 PrefRegistrySyncable::UNSYNCABLE_PREF);
   registry->RegisterIntegerPref(prefs::kProfileAvatarIndex,
                                 -1,
                                 PrefRegistrySyncable::SYNCABLE_PREF);
   registry->RegisterStringPref(prefs::kProfileName,
                                "",
                                PrefRegistrySyncable::SYNCABLE_PREF);
   registry->RegisterBooleanPref(prefs::kProfileIsManaged,
@@ skipping 890 matching lines @@
                                      base::FilePath* cache_path,
                                      int* max_size) {
   DCHECK(cache_path);
   DCHECK(max_size);
   base::FilePath path(prefs_->GetFilePath(prefs::kDiskCacheDir));
   if (!path.empty())
     *cache_path = path;
   *max_size = is_media_context ? prefs_->GetInteger(prefs::kMediaCacheSize) :
                                  prefs_->GetInteger(prefs::kDiskCacheSize);
 }