Add utf_string_conversions to base namespace.

chrome/test/webdriver/commands/file_upload_command.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/test/webdriver/commands/file_upload_command.h"
 
 #include "base/file_util.h"
 #include "base/utf_string_conversions.h"
 #include "base/values.h"
 #include "build/build_config.h"
@@ skipping 36 matching lines @@
     return;
   }
   std::string error_msg;
   base::FilePath upload;
   if (!UnzipSoleFile(upload_dir, zip_data, &upload, &error_msg)) {
     response->SetError(new Error(kUnknownError, error_msg));
     return;
   }
 
 #if defined(OS_WIN)
-  response->SetValue(new base::StringValue(WideToUTF8(upload.value())));
+  response->SetValue(new base::StringValue(base::WideToUTF8(upload.value())));
 #else
   response->SetValue(new base::StringValue(upload.value()));
 #endif
 }
 
 }  // namespace webdriver