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

chrome/browser/chromeos/login/easy_unlock/bootstrap_manager.cc

 // Copyright 2015 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/login/easy_unlock/bootstrap_manager.h"
 
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
 #include "base/prefs/scoped_user_pref_update.h"
 #include "chrome/browser/browser_process.h"
@@ skipping 13 matching lines @@
   registry->RegisterListPref(kPendingEasyBootstrapUsers);
 }
 
 BootstrapManager::BootstrapManager(Delegate* delegate)
     : delegate_(delegate) {
 }
 
 BootstrapManager::~BootstrapManager() {
 }
 
-void BootstrapManager::AddPendingBootstrap(const std::string& user_id) {
+void BootstrapManager::AddPendingBootstrap(const user_manager::UserID& user_id) {
   DCHECK(!user_id.empty());
   PrefService* local_state = g_browser_process->local_state();
 
   ListPrefUpdate update(local_state, kPendingEasyBootstrapUsers);
-  update->AppendString(user_id);
+  update->AppendString(user_id.GetUserEmail());
 }
 
-void BootstrapManager::FinishPendingBootstrap(const std::string& user_id) {
+void BootstrapManager::FinishPendingBootstrap(const user_manager::UserID& user_id) {
   PrefService* local_state = g_browser_process->local_state();
 
   ListPrefUpdate update(local_state, kPendingEasyBootstrapUsers);
   for (size_t i = 0; i < update->GetSize(); ++i) {
     std::string current_user;
-    if (update->GetString(i, &current_user) && user_id == current_user) {
+    if (update->GetString(i, &current_user) && user_id.GetUserEmail() == current_user) {
       update->Remove(i, NULL);
       break;
     }
   }
 }
 
 void BootstrapManager::RemoveAllPendingBootstrap() {
   PrefService* local_state = g_browser_process->local_state();
 
   const base::ListValue* users =
       local_state->GetList(kPendingEasyBootstrapUsers);
   for (size_t i = 0; i < users->GetSize(); ++i) {
-    std::string current_user;
-    if (users->GetString(i, &current_user))
-      delegate_->RemovePendingBootstrapUser(current_user);
+    std::string current_user_email;
+    if (users->GetString(i, &current_user_email))
+      delegate_->RemovePendingBootstrapUser(user_manager::UserID::FromUserEmail(current_user_email));
   }
 
   local_state->ClearPref(kPendingEasyBootstrapUsers);
   local_state->CommitPendingWrite();
 }
 
-bool BootstrapManager::HasPendingBootstrap(const std::string& user_id) const {
+bool BootstrapManager::HasPendingBootstrap(const user_manager::UserID& user_id) const {
   PrefService* local_state = g_browser_process->local_state();
 
   const base::ListValue* users =
       local_state->GetList(kPendingEasyBootstrapUsers);
   for (size_t i = 0; i < users->GetSize(); ++i) {
-    std::string current_user;
-    if (users->GetString(i, &current_user) && user_id == current_user)
+    std::string current_user_email;
+    if (users->GetString(i, &current_user_email) && user_id.GetUserEmail() == current_user_email)
       return true;
   }
   return false;
 }
 
 }  // namespace chromeos