Use a direct include of strings headers in base/.

base/prefs/pref_registry_simple.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/pref_registry_simple.h"
 
 #include "base/files/file_path.h"
-#include "base/string_number_conversions.h"
+#include "base/strings/string_number_conversions.h"
 #include "base/values.h"
 
 PrefRegistrySimple::PrefRegistrySimple() {
 }
 
 PrefRegistrySimple::~PrefRegistrySimple() {
 }
 
 void PrefRegistrySimple::RegisterBooleanPref(const char* path,
                                              bool default_value) {
@@ skipping 39 matching lines @@
     const char* path,
     base::DictionaryValue* default_value) {
   RegisterPreference(path, default_value);
 }
 
 void PrefRegistrySimple::RegisterInt64Pref(const char* path,
                                            int64 default_value) {
   RegisterPreference(
       path, base::Value::CreateStringValue(base::Int64ToString(default_value)));
 }