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

chrome/browser/chromeos/proxy_config_service_impl.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/chromeos/proxy_config_service_impl.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/callback.h"
 #include "base/location.h"
@@ skipping 134 matching lines @@
     // but the proxy is determined by user policy.
     // See https://crbug.com/454966 .
     VLOG(1) << "Respect proxy from user policy although network is shared.";
     return false;
   }
   if (onc_source == ::onc::ONC_SOURCE_DEVICE_POLICY) {
     policy::BrowserPolicyConnectorChromeOS* connector =
         g_browser_process->platform_part()->browser_policy_connector_chromeos();
     const user_manager::User* logged_in_user =
         user_manager::UserManager::Get()->GetLoggedInUser();
-    if (connector->GetUserAffiliation(logged_in_user->email()) ==
+    if (connector->GetUserAffiliation(logged_in_user->GetUserID()) ==
         policy::USER_AFFILIATION_MANAGED) {
       VLOG(1) << "Respecting proxy for network, as logged-in user belongs to "
               << "the domain the device is enrolled to.";
       return false;
     }
   }
 
   // This network is shared and not managed by the user's domain.
   bool use_shared_proxies = profile_prefs->GetBoolean(prefs::kUseSharedProxies);
   VLOG(1) << "Use proxy of shared network: " << use_shared_proxies;
@@ skipping 66 matching lines @@
     if (VLOG_IS_ON(1) && !update_pending()) {  // Update was successful.
       scoped_ptr<base::DictionaryValue> config_dict(effective_config.ToValue());
       VLOG(1) << this << ": Proxy changed: "
               << ProxyPrefs::ConfigStateToDebugString(active_config_state_)
               << ", " << *config_dict;
     }
   }
 }
 
 }  // namespace chromeos