Cleanup and style guideline conformance for policy implementation

chrome/browser/prefs/default_pref_store.cc

 // Copyright (c) 2010 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/prefs/default_pref_store.h"
 
 #include "base/values.h"
 
 DefaultPrefStore::DefaultPrefStore() : prefs_(new DictionaryValue()) {
 }
 
 DefaultPrefStore::~DefaultPrefStore() {
 }
 
-DictionaryValue* DefaultPrefStore::prefs() {
+DictionaryValue* DefaultPrefStore::prefs() const {
   return prefs_.get();
 }
 
 PrefStore::PrefReadError DefaultPrefStore::ReadPrefs() {
   return PrefStore::PREF_READ_ERROR_NONE;
 }