Add utf_string_conversions to base namespace.

chrome/browser/download/save_package_file_picker.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 "chrome/browser/download/save_package_file_picker.h"
 
 #include "base/command_line.h"
 #include "base/metrics/histogram.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/public/pref_member.h"
@@ skipping 193 matching lines @@
 
     UMA_HISTOGRAM_ENUMERATION("Download.SavePageType",
                               save_type,
                               content::SAVE_PAGE_TYPE_MAX);
 
     StringPrefMember save_file_path;
     save_file_path.Init(prefs::kSaveFileDefaultDirectory, prefs);
 #if defined(OS_POSIX)
     std::string path_string = path.DirName().value();
 #elif defined(OS_WIN)
-    std::string path_string = WideToUTF8(path.DirName().value());
+    std::string path_string = base::WideToUTF8(path.DirName().value());
 #endif
     // If user change the default saving directory, we will remember it just
     // like IE and FireFox.
     if (!process->GetBrowserContext()->IsOffTheRecord() &&
         save_file_path.GetValue() != path_string)
       save_file_path.SetValue(path_string);
 
     callback_.Run(path, save_type, base::Bind(&OnSavePackageDownloadCreated));
   }
 
   delete this;
 }
 
 void SavePackageFilePicker::FileSelectionCanceled(void* unused_params) {
   delete this;
 }