We should use UserID object to identify users instead of username.

chrome/browser/chromeos/platform_keys/platform_keys_nss.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 "chrome/browser/chromeos/platform_keys/platform_keys.h"
 
 #include <cert.h>
 #include <cryptohi.h>
 #include <keyhi.h>
 #include <secder.h>
@@ skipping 11 matching lines @@
 #include "base/threading/worker_pool.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/browser_process_platform_part_chromeos.h"
 #include "chrome/browser/chromeos/net/client_cert_filter_chromeos.h"
 #include "chrome/browser/chromeos/policy/browser_policy_connector_chromeos.h"
 #include "chrome/browser/chromeos/profiles/profile_helper.h"
 #include "chrome/browser/extensions/api/enterprise_platform_keys/enterprise_platform_keys_api.h"
 #include "chrome/browser/net/nss_context.h"
 #include "chrome/browser/profiles/profile.h"
 #include "components/policy/core/common/cloud/cloud_policy_constants.h"
+#include "components/user_manager/user_id.h"
 #include "content/public/browser/browser_context.h"
 #include "content/public/browser/browser_thread.h"
 #include "crypto/nss_key_util.h"
 #include "crypto/scoped_nss_types.h"
 #include "net/base/crypto_module.h"
 #include "net/base/net_errors.h"
 #include "net/cert/cert_database.h"
 #include "net/cert/nss_cert_database.h"
 #include "net/cert/x509_certificate.h"
 #include "net/cert/x509_util_nss.h"
@@ skipping 732 matching lines @@
   cert_request_info->cert_authorities = certificate_authorities;
 
   const user_manager::User* user =
       chromeos::ProfileHelper::Get()->GetUserByProfile(
           Profile::FromBrowserContext(browser_context));
 
   // Use the device-wide system key slot only if the user is of the same
   // domain as the device is registered to.
   policy::BrowserPolicyConnectorChromeOS* connector =
       g_browser_process->platform_part()->browser_policy_connector_chromeos();
-  bool use_system_key_slot = connector->GetUserAffiliation(user->email()) ==
+  bool use_system_key_slot = connector->GetUserAffiliation(user->GetUserID()) ==
                              policy::USER_AFFILIATION_MANAGED;
 
   scoped_ptr<SelectCertificatesState> state(new SelectCertificatesState(
       user->username_hash(), use_system_key_slot, cert_request_info, callback));
 
   BrowserThread::PostTask(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&SelectCertificatesOnIOThread, base::Passed(&state)));
 }
 
@@ skipping 98 matching lines @@
   NSSOperationState* state_ptr = state.get();
   GetCertDatabase(std::string() /* don't get any specific slot */,
                   base::Bind(&GetTokensWithDB, base::Passed(&state)),
                   browser_context,
                   state_ptr);
 }
 
 }  // namespace platform_keys
 
 }  // namespace chromeos