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

chrome/browser/supervised_user/chromeos/manager_password_service.cc

Index: chrome/browser/supervised_user/chromeos/manager_password_service.cc
diff --git a/chrome/browser/supervised_user/chromeos/manager_password_service.cc b/chrome/browser/supervised_user/chromeos/manager_password_service.cc
index 30f0a055b57fc86d51958dbe15e730fc4ad23d84..ad6d4b4cf0f889ca118c8c5b3b07fad66e95c2eb 100644
--- a/chrome/browser/supervised_user/chromeos/manager_password_service.cc
+++ b/chrome/browser/supervised_user/chromeos/manager_password_service.cc
@@ -22,12 +22,12 @@
 
 namespace chromeos {
 
-ManagerPasswordService::ManagerPasswordService() : weak_ptr_factory_(this) {}
+ManagerPasswordService::ManagerPasswordService() : user_id_(std::string(), std::string()), weak_ptr_factory_(this) {}
 
 ManagerPasswordService::~ManagerPasswordService() {}
 
 void ManagerPasswordService::Init(
-    const std::string& user_id,
+    const user_manager::UserID& user_id,
     SupervisedUserSyncService* user_service,
     SupervisedUserSharedSettingsService* shared_settings_service) {
   user_id_ = user_id;
@@ -46,10 +46,10 @@ void ManagerPasswordService::Init(
            user_manager::UserManager::Get()->GetUsers()) {
     if (user->GetType() != user_manager::USER_TYPE_SUPERVISED)
       continue;
-    if (user_id != supervised_user_manager->GetManagerUserId(user->email()))
+    if (user_id != supervised_user_manager->GetManagerUserId(user->GetUserID()))
       continue;
     OnSharedSettingsChange(
-        supervised_user_manager->GetUserSyncId(user->email()),
+        supervised_user_manager->GetUserSyncId(user->GetUserID()),
         supervised_users::kChromeOSPasswordData);
   }
 }
@@ -82,8 +82,8 @@ void ManagerPasswordService::OnSharedSettingsChange(
   SupervisedUserAuthentication* auth =
       supervised_user_manager->GetAuthentication();
 
-  if (!auth->NeedPasswordChange(user->email(), dict) &&
-      !auth->HasIncompleteKey(user->email())) {
+  if (!auth->NeedPasswordChange(user->GetUserID(), dict) &&
+      !auth->HasIncompleteKey(user->GetUserID())) {
     return;
   }
   scoped_ptr<base::DictionaryValue> wrapper(dict->DeepCopy());
@@ -91,13 +91,13 @@ void ManagerPasswordService::OnSharedSettingsChange(
       base::Bind(&ManagerPasswordService::GetSupervisedUsersCallback,
                  weak_ptr_factory_.GetWeakPtr(),
                  su_id,
-                 user->email(),
+                 user->GetUserID(),
                  Passed(&wrapper)));
 }
 
 void ManagerPasswordService::GetSupervisedUsersCallback(
     const std::string& sync_su_id,
-    const std::string& user_id,
+    const user_manager::UserID& user_id,
     scoped_ptr<base::DictionaryValue> password_data,
     const base::DictionaryValue* supervised_users) {
   const base::DictionaryValue* supervised_user = NULL;
@@ -108,7 +108,7 @@ void ManagerPasswordService::GetSupervisedUsersCallback(
   std::string signature_key;
   if (!supervised_user->GetString(SupervisedUserSyncService::kMasterKey,
                                   &master_key)) {
-    LOG(WARNING) << "Can not apply password change to " << user_id
+    LOG(WARNING) << "Can not apply password change to " << user_id.GetUserEmail()
                  << ": no master key found";
     UMA_HISTOGRAM_ENUMERATION(
         "ManagedUsers.ChromeOS.PasswordChange",
@@ -122,7 +122,7 @@ void ManagerPasswordService::GetSupervisedUsersCallback(
       !supervised_user->GetString(
           SupervisedUserSyncService::kPasswordEncryptionKey,
           &encryption_key)) {
-    LOG(WARNING) << "Can not apply password change to " << user_id
+    LOG(WARNING) << "Can not apply password change to " << user_id.GetUserEmail()
                  << ": no signature / encryption keys.";
     UMA_HISTOGRAM_ENUMERATION(
         "ManagedUsers.ChromeOS.PasswordChange",
@@ -146,7 +146,7 @@ void ManagerPasswordService::GetSupervisedUsersCallback(
   has_data &= password_data->GetIntegerWithoutPathExpansion(kPasswordRevision,
                                                             &revision);
   if (!has_data) {
-    LOG(WARNING) << "Can not apply password change to " << user_id
+    LOG(WARNING) << "Can not apply password change to " << user_id.GetUserEmail()
                  << ": incomplete password data.";
     UMA_HISTOGRAM_ENUMERATION(
         "ManagedUsers.ChromeOS.PasswordChange",
@@ -190,9 +190,9 @@ void ManagerPasswordService::OnAuthenticationFailure(
 
 void ManagerPasswordService::OnAddKeySuccess(
     const UserContext& master_key_context,
-    const std::string& user_id,
+    const user_manager::UserID& user_id,
     scoped_ptr<base::DictionaryValue> password_data) {
-  VLOG(0) << "Password changed for " << user_id;
+  VLOG(0) << "Password changed for " << user_id.GetUserEmail();
   UMA_HISTOGRAM_ENUMERATION(
       "ManagedUsers.ChromeOS.PasswordChange",
       SupervisedUserAuthentication::PASSWORD_CHANGED_IN_MANAGER_SESSION,
@@ -240,7 +240,7 @@ void ManagerPasswordService::OnKeyTransformedIfNeeded(
 
 void ManagerPasswordService::OnNewManagerKeySuccess(
     const UserContext& master_key_context) {
-  VLOG(1) << "Added new master key for " << master_key_context.GetUserID();
+  VLOG(1) << "Added new master key for " << master_key_context.GetUserID().GetUserEmail();
   authenticator_->RemoveKey(
       master_key_context,
       kLegacyCryptohomeSupervisedUserKeyLabel,
@@ -252,7 +252,7 @@ void ManagerPasswordService::OnNewManagerKeySuccess(
 void ManagerPasswordService::OnOldSupervisedUserKeyDeleted(
     const UserContext& master_key_context) {
   VLOG(1) << "Removed old supervised user key for "
-          << master_key_context.GetUserID();
+          << master_key_context.GetUserID().GetUserEmail();
   authenticator_->RemoveKey(
       master_key_context,
       kLegacyCryptohomeMasterKeyLabel,
@@ -263,7 +263,7 @@ void ManagerPasswordService::OnOldSupervisedUserKeyDeleted(
 
 void ManagerPasswordService::OnOldManagerKeyDeleted(
     const UserContext& master_key_context) {
-  VLOG(1) << "Removed old master key for " << master_key_context.GetUserID();
+  VLOG(1) << "Removed old master key for " << master_key_context.GetUserID().GetUserEmail();
 }
 
 void ManagerPasswordService::Shutdown() {