Remove wstring from autocomplete.

chrome/browser/extensions/extension_omnibox_api.cc

 // 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.
 
 #include "chrome/browser/extensions/extension_omnibox_api.h"
 
 #include "base/json/json_writer.h"
 #include "base/lazy_instance.h"
 #include "base/string_util.h"
 #include "base/utf_string_conversions.h"
@@ skipping 243 matching lines @@
     string16 replacement =
         remaining_input.empty() ? kReplacementText : remaining_input;
     description.replace(placeholder, kPlaceholderText.length(), replacement);
 
     for (size_t i = 0; i < description_styles.size(); ++i) {
       if (description_styles[i].offset > placeholder)
         description_styles[i].offset += replacement.length() - 2;
     }
   }
 
-  match->contents.assign(UTF16ToWide(description));
+  match->contents.assign(description);
 }