Rewrite DefaultPrefStore for performance

base/prefs/value_map_pref_store.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 "base/prefs/value_map_pref_store.h"
 
 #include <algorithm>
 
 #include "base/stl_util.h"
 #include "base/values.h"
@@ skipping 10 matching lines @@
 }
 
 void ValueMapPrefStore::RemoveObserver(PrefStore::Observer* observer) {
   observers_.RemoveObserver(observer);
 }
 
 size_t ValueMapPrefStore::NumberOfObservers() const {
   return observers_.size();
 }
 
-ValueMapPrefStore::iterator ValueMapPrefStore::begin() {
-  return prefs_.begin();
-}
-
-ValueMapPrefStore::iterator ValueMapPrefStore::end() {
-  return prefs_.end();
-}
-
-ValueMapPrefStore::const_iterator ValueMapPrefStore::begin() const {
-  return prefs_.begin();
-}
-
-ValueMapPrefStore::const_iterator ValueMapPrefStore::end() const {
-  return prefs_.end();
-}
-
 ValueMapPrefStore::~ValueMapPrefStore() {}
 
 void ValueMapPrefStore::SetValue(const std::string& key, Value* value) {
   if (prefs_.SetValue(key, value))
     FOR_EACH_OBSERVER(Observer, observers_, OnPrefValueChanged(key));
 }
 
 void ValueMapPrefStore::RemoveValue(const std::string& key) {
   if (prefs_.RemoveValue(key))
     FOR_EACH_OBSERVER(Observer, observers_, OnPrefValueChanged(key));
 }
 
 void ValueMapPrefStore::NotifyInitializationCompleted() {
   FOR_EACH_OBSERVER(Observer, observers_, OnInitializationCompleted(true));
 }