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

chrome/browser/chromeos/policy/user_cloud_policy_manager_chromeos.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/policy/user_cloud_policy_manager_chromeos.h"
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
@@ skipping 37 matching lines @@
     "Enterprise.UserPolicyChromeOS.InitialFetch.DelayOAuth2Token";
 const char kUMAInitialFetchDelayPolicyFetch[] =
     "Enterprise.UserPolicyChromeOS.InitialFetch.DelayPolicyFetch";
 const char kUMAInitialFetchDelayTotal[] =
     "Enterprise.UserPolicyChromeOS.InitialFetch.DelayTotal";
 const char kUMAInitialFetchOAuth2Error[] =
     "Enterprise.UserPolicyChromeOS.InitialFetch.OAuth2Error";
 const char kUMAInitialFetchOAuth2NetworkError[] =
     "Enterprise.UserPolicyChromeOS.InitialFetch.OAuth2NetworkError";
 
-void OnWildcardCheckCompleted(const std::string& username,
+void OnWildcardCheckCompleted(const user_manager::UserID& user_id,
                               WildcardLoginChecker::Result result) {
   if (result == WildcardLoginChecker::RESULT_BLOCKED) {
     LOG(ERROR) << "Online wildcard login check failed, terminating session.";
 
     // TODO(mnissler): This only removes the user pod from the login screen, but
     // the cryptohome remains. This is because deleting the cryptohome for a
     // logged-in session is not possible. Fix this either by delaying the
     // cryptohome deletion operation or by getting rid of the in-session
     // wildcard check.
-    user_manager::UserManager::Get()->RemoveUserFromList(username);
+    user_manager::UserManager::Get()->RemoveUserFromList(user_id);
     chrome::AttemptUserExit();
   }
 }
 
 }  // namespace
 
 UserCloudPolicyManagerChromeOS::UserCloudPolicyManagerChromeOS(
     scoped_ptr<CloudPolicyStore> store,
     scoped_ptr<CloudExternalDataManager> external_data_manager,
     const base::FilePath& component_policy_cache_path,
     bool wait_for_policy_fetch,
     base::TimeDelta initial_policy_fetch_timeout,
     const scoped_refptr<base::SequencedTaskRunner>& task_runner,
     const scoped_refptr<base::SequencedTaskRunner>& file_task_runner,
     const scoped_refptr<base::SequencedTaskRunner>& io_task_runner)
     : CloudPolicyManager(dm_protocol::kChromeUserPolicyType,
                          std::string(),
                          store.get(),
                          task_runner,
                          file_task_runner,
                          io_task_runner),
       store_(store.Pass()),
       external_data_manager_(external_data_manager.Pass()),
+      wildcard_user_id_(std::string(), std::string()),
       component_policy_cache_path_(component_policy_cache_path),
       wait_for_policy_fetch_(wait_for_policy_fetch),
       policy_fetch_timeout_(false, false) {
   time_init_started_ = base::Time::Now();
   if (wait_for_policy_fetch_ && !initial_policy_fetch_timeout.is_max()) {
     policy_fetch_timeout_.Start(
         FROM_HERE,
         initial_policy_fetch_timeout,
         base::Bind(&UserCloudPolicyManagerChromeOS::OnBlockingFetchTimeout,
                    base::Unretained(this)));
@@ skipping 37 matching lines @@
     OnInitializationCompleted(service());
   } else {
     service()->AddObserver(this);
   }
 }
 
 void UserCloudPolicyManagerChromeOS::OnAccessTokenAvailable(
     const std::string& access_token) {
   access_token_ = access_token;
 
-  if (!wildcard_username_.empty()) {
+  if (!wildcard_user_id_.empty()) {
     wildcard_login_checker_.reset(new WildcardLoginChecker());
     wildcard_login_checker_->StartWithAccessToken(
         access_token,
-        base::Bind(&OnWildcardCheckCompleted, wildcard_username_));
+        base::Bind(&OnWildcardCheckCompleted, wildcard_user_id_));
   }
 
   if (service() && service()->IsInitializationComplete() &&
       client() && !client()->is_registered()) {
     OnOAuth2PolicyTokenFetched(
         access_token, GoogleServiceAuthError(GoogleServiceAuthError::NONE));
   }
 }
 
 bool UserCloudPolicyManagerChromeOS::IsClientRegistered() const {
   return client() && client()->is_registered();
 }
 
 void UserCloudPolicyManagerChromeOS::EnableWildcardLoginCheck(
-    const std::string& username) {
+    const user_manager::UserID& user_id) {
   DCHECK(access_token_.empty());
-  wildcard_username_ = username;
+  wildcard_user_id_ = user_id;
 }
 
 void UserCloudPolicyManagerChromeOS::Shutdown() {
   if (client())
     client()->RemoveObserver(this);
   if (service())
     service()->RemoveObserver(this);
   token_fetcher_.reset();
   external_data_manager_->Disconnect();
   CloudPolicyManager::Shutdown();
@@ skipping 217 matching lines @@
     // OnComponentCloudPolicyUpdated() once it's ready.
     return;
   }
 
   core()->StartRefreshScheduler();
   core()->TrackRefreshDelayPref(local_state_,
                                 policy_prefs::kUserPolicyRefreshRate);
 }
 
 }  // namespace policy