base: Get rid of 'using' declaration of StringAppendF.

net/url_request/url_request_job_metrics.cc

 // Copyright (c) 2006-2008 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 "net/url_request/url_request_job_metrics.h"
 
 #include "base/basictypes.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
 
@@ skipping 13 matching lines @@
 
   text->append(L"job url = ");
   text->append(UTF8ToWide(original_url_->spec()));
 
   if (url_.get()) {
     text->append(L"; redirected url = ");
     text->append(UTF8ToWide(url_->spec()));
   }
 
   TimeDelta elapsed = end_time_ - start_time_;
-  StringAppendF(text,
+  base::StringAppendF(text,
       L"; total bytes read = %ld; read calls = %d; time = %lld ms;",
       static_cast<long>(total_bytes_read_),
       number_of_read_IO_, elapsed.InMilliseconds());
 
   if (success_) {
     text->append(L" success.");
   } else {
     text->append(L" fail.");
   }
 }