Use a direct include of strings headers in extensions/, google_apis/, gpu/.

google_apis/gaia/oauth2_mint_token_flow.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 "google_apis/gaia/oauth2_mint_token_flow.h"
 
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/command_line.h"
 #include "base/json/json_reader.h"
 #include "base/message_loop.h"
-#include "base/string_util.h"
-#include "base/stringprintf.h"
 #include "base/strings/string_number_conversions.h"
+#include "base/strings/string_util.h"
+#include "base/strings/stringprintf.h"
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "google_apis/gaia/gaia_urls.h"
 #include "google_apis/gaia/google_service_auth_error.h"
 #include "net/base/escape.h"
 #include "net/url_request/url_fetcher.h"
 #include "net/url_request/url_request_context_getter.h"
 #include "net/url_request/url_request_status.h"
 
 using net::URLFetcher;
@@ skipping 219 matching lines @@
     for (size_t i = 0; i < entry.details.size(); i++)
       TrimWhitespace(entry.details[i], TRIM_ALL, &entry.details[i]);
     issue_advice->push_back(entry);
   }
 
   if (!success)
     issue_advice->clear();
 
   return success;
 }