Use a direct include of strings headers in chromeos/.

chromeos/network/network_event_log.h

 // 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.
 
 #ifndef CHROMEOS_NETWORK_NETWORK_EVENT_LOG_H_
 #define CHROMEOS_NETWORK_NETWORK_EVENT_LOG_H_
 
 #include <deque>
 #include <string>
 
 #include "base/basictypes.h"
-#include "base/stringprintf.h"
+#include "base/strings/stringprintf.h"
 #include "base/time.h"
 #include "chromeos/chromeos_export.h"
 
 namespace base {
 class Value;
 }
 
 namespace chromeos {
 
 // Namespace for functions for logging network events.
@@ skipping 86 matching lines @@
 // Macro to include file and line number info in the event log.
 #define NET_LOG_LEVEL(log_level, event, description)            \
   ::chromeos::network_event_log::internal::AddEntry(            \
       __FILE__, __LINE__, log_level, event, description)
 
 }  // namespace network_event_log
 
 }  // namespace chromeos
 
 #endif  // CHROMEOS_NETWORK_NETWORK_EVENT_LOG_H_