Revert of Move base/prefs to components/prefs

components/prefs/scoped_user_pref_update.cc

-// Copyright 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.
-
-#include "base/prefs/scoped_user_pref_update.h"
-
-#include "base/logging.h"
-#include "base/prefs/pref_notifier.h"
-#include "base/prefs/pref_service.h"
-
-namespace subtle {
-
-ScopedUserPrefUpdateBase::ScopedUserPrefUpdateBase(PrefService* service,
-                                                   const std::string& path)
-    : service_(service), path_(path), value_(NULL) {
-  DCHECK(service_->CalledOnValidThread());
-}
-
-ScopedUserPrefUpdateBase::~ScopedUserPrefUpdateBase() {
-  Notify();
-}
-
-base::Value* ScopedUserPrefUpdateBase::GetValueOfType(base::Value::Type type) {
-  DCHECK(CalledOnValidThread());
-  if (!value_)
-    value_ = service_->GetMutableUserPref(path_, type);
-  return value_;
-}
-
-void ScopedUserPrefUpdateBase::Notify() {
-  if (value_) {
-    service_->ReportUserPrefChanged(path_);
-    value_ = NULL;
-  }
-}
-
-}  // namespace subtle