iwyu: Include stringprintf.h where appropriate, part 2.

chrome/service/cloud_print/cloud_print_url_fetcher.cc

 // Copyright (c) 2011 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/service/cloud_print/cloud_print_url_fetcher.h"
 
-#include "base/string_util.h"
+#include "base/stringprintf.h"
 #include "base/values.h"
 #include "chrome/common/net/http_return.h"
 #include "chrome/service/cloud_print/cloud_print_consts.h"
 #include "chrome/service/cloud_print/cloud_print_helpers.h"
 #include "chrome/service/cloud_print/cloud_print_token_store.h"
 #include "chrome/service/net/service_url_request_context.h"
 #include "chrome/service/service_process.h"
 #include "googleurl/src/gurl.h"
 #include "net/url_request/url_request_status.h"
 
@@ skipping 152 matching lines @@
 
 net::URLRequestContextGetter* CloudPrintURLFetcher::GetRequestContextGetter() {
   ServiceURLRequestContextGetter* getter =
       g_service_process->GetServiceURLRequestContextGetter();
   // Now set up the user agent for cloudprint.
   std::string user_agent = getter->user_agent();
   base::StringAppendF(&user_agent, " %s", kCloudPrintUserAgent);
   getter->set_user_agent(user_agent);
   return getter;
 }