Enable system token in platformKeys api.

chrome/browser/chromeos/platform_keys/platform_keys.cc

 // Copyright 2014 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 "chromeos/login/auth/auth_attempt_state_resolver.h"
+#include "chrome/browser/chromeos/platform_keys/platform_keys.h"
 
 namespace chromeos {
 
-AuthAttemptStateResolver::AuthAttemptStateResolver() {
-}
+namespace platform_keys {
 
-AuthAttemptStateResolver::~AuthAttemptStateResolver() {
-}
+const char kTokenIdUser[] = "user";
+const char kTokenIdSystem[] = "system";
+
+}  // namespace platform_keys
 
 }  // namespace chromeos