base: Remove 'using' declaration of StringAppendV.

skia/ext/google_logging.cc

-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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.
 
 // This file provides integration with Google-style "base/logging.h" assertions
 // for Skia SkASSERT. If you don't want this, you can link with another file
 // that provides integration with the logging of your choice.
 
 #include "base/logging.h"
 #include "base/string_util.h"
 
 void SkDebugf_FileLine(const char* file, int line, bool fatal,
                        const char* format, ...) {
   va_list ap;
   va_start(ap, format);
 
   std::string msg;
-  StringAppendV(&msg, format, ap);
+  base::StringAppendV(&msg, format, ap);
 
   logging::LogMessage(file, line,
                       fatal ? logging::LOG_FATAL : logging::LOG_INFO).stream()
       << msg;
 }