Use a direct include of strings headers in webkit/, part 1.

webkit/common/user_agent/user_agent_util_ios.mm

 // Copyright 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 "webkit/common/user_agent/user_agent_util.h"
 
 #import <UIKit/UIKit.h>
 
 #include <sys/sysctl.h>
 #include <string>
 
 #include "base/memory/scoped_nsobject.h"
-#include "base/string_util.h"
-#include "base/stringprintf.h"
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
 #include "base/strings/sys_string_conversions.h"
 #include "base/sys_info.h"
 
 namespace {
 
 struct UAVersions {
   const char* safari_version_string;
   const char* webkit_version_string;
 };
 
@@ skipping 145 matching lines @@
       webkit_glue::BuildOSCpuInfo().c_str(),
       ua_versions.webkit_version_string,
       product.c_str(),
       kernel_version,
       ua_versions.safari_version_string);
 
   return user_agent;
 }
 
 }  // namespace webkit_glue