Update some uses of UTF conversions in chrome/browser to use the base:: namespace.

chrome/browser/ui/autofill/country_combobox_model.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/ui/autofill/country_combobox_model.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "chrome/browser/browser_process.h"
 #include "components/autofill/core/browser/autofill_country.h"
 #include "components/autofill/core/browser/personal_data_manager.h"
@@ skipping 36 matching lines @@
   return countries_.size();
 }
 
 base::string16 CountryComboboxModel::GetItemAt(int index) {
   AutofillCountry* country = countries_[index];
   if (country)
     return countries_[index]->name();
 
   // The separator item. Implemented for platforms that don't yet support
   // IsItemSeparatorAt().
-  return ASCIIToUTF16("---");
+  return base::ASCIIToUTF16("---");
 }
 
 bool CountryComboboxModel::IsItemSeparatorAt(int index) {
   return !countries_[index];
 }
 
 }  // namespace autofill