Rewrite std::string("") to std::string(), Linux edition.

chrome/browser/net/url_info.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/net/url_info.h"
 
 #include <ctype.h>
 #include <math.h>
 
 #include <algorithm>
@@ skipping 343 matching lines @@
     case NO_PREFETCH_MOTIVATION:
       return "n/a";
 
     case STATIC_REFERAL_MOTIVATED:
       return RemoveJs(referring_url_.spec()) + "*";
 
     case LEARNED_REFERAL_MOTIVATED:
       return RemoveJs(referring_url_.spec());
 
     default:
-      return "";
+      return std::string();
   }
 }
 
 }  // namespace chrome_browser_net