Use a direct include of strings headers in chrome_frame/.

chrome_frame/registry_list_preferences_holder.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_frame/registry_list_preferences_holder.h"
 
-#include "base/string_util.h"
+#include "base/strings/string_util.h"
 #include "base/win/registry.h"
 
 RegistryListPreferencesHolder::RegistryListPreferencesHolder() : valid_(false) {
 }
 
 void RegistryListPreferencesHolder::Init(HKEY hive,
                                          const wchar_t* registry_path,
                                          const wchar_t* list_name) {
   string16 list_path(registry_path);
   list_path += L"\\";
@@ skipping 18 matching lines @@
 
 void RegistryListPreferencesHolder::AddStringForTesting(
     const string16& string) {
   values_.push_back(string);
 }
 
 void RegistryListPreferencesHolder::ResetForTesting() {
   values_.clear();
   valid_ = false;
 }