Add more string_util functions to base namespace.

ash/system/user/login_status.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 "ash/system/user/login_status.h"
 
 #include "ash/session/session_state_delegate.h"
 #include "ash/shell.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
@@ skipping 23 matching lines @@
       break;
   }
   base::string16 message =
       ui::ResourceBundle::GetSharedInstance().GetLocalizedString(message_id);
   // Desirable line breaking points are marked using \n. As the resource
   // framework does not evaluate escape sequences, the \n need to be explicitly
   // handled. Depending on the value of |multiline|, actual line breaks or
   // spaces are substituted.
   base::string16 newline = multiline ? base::ASCIIToUTF16("\n")
                                      : base::ASCIIToUTF16(" ");
-  ReplaceSubstringsAfterOffset(&message, 0, base::ASCIIToUTF16("\\n"), newline);
+  base::ReplaceSubstringsAfterOffset(
+      &message, 0, base::ASCIIToUTF16("\\n"), newline);
   return message;
 }
 
 }  // namespace user
 }  // namespace ash