mac: Update signature of ShowOneClickSigninDialog() to match declaration.

chrome/browser/ui/cocoa/one_click_signin_dialog_mac.mm

 // 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 <string>
 
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/browser/ui/sync/one_click_signin_dialog.h"
 
 void ShowOneClickSigninDialog(Profile* profile,
+                              const std::string& session_index,
                               const std::string& email,
                               const std::string& password) {
   // TODO(rogerta): cocoa dialog not yet implemented.  See
   // one_click_signin_dialog_view.cc for what needs to be done here.
 }