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

chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc

Index: chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc
diff --git a/chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc b/chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc
index 815fa789ada0bd408a9cf68ca0b911f3d5b08416..c17874ad0fd92b2fef5cbe39d098778e4d2b9a7f 100644
--- a/chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc
+++ b/chrome/browser/ui/webui/options/chromeos/core_chromeos_options_handler.cc
@@ -62,15 +62,15 @@ bool IsSettingShared(const std::string& pref) {
 
 // Creates a user info dictionary to be stored in the |ListValue| that is
 // passed to Javascript for the |kAccountsPrefUsers| preference.
-base::DictionaryValue* CreateUserInfo(const std::string& username,
+base::DictionaryValue* CreateUserInfo(const user_manager::UserID& user_id,
                                       const std::string& display_email,
                                       const std::string& display_name) {
   base::DictionaryValue* user_dict = new base::DictionaryValue;
-  user_dict->SetString("username", username);
+  user_dict->SetString("username", user_id.GetUserEmail());
   user_dict->SetString("name", display_email);
   user_dict->SetString("email", display_name);
 
-  bool is_owner = user_manager::UserManager::Get()->GetOwnerEmail() == username;
+  bool is_owner = user_manager::UserManager::Get()->GetOwnerID() == user_id;
   user_dict->SetBoolean("owner", is_owner);
   return user_dict;
 }
@@ -87,10 +87,11 @@ base::Value* CreateUsersWhitelist(const base::Value *pref_value) {
        i != list_value->end(); ++i) {
     std::string email;
     if ((*i)->GetAsString(&email)) {
+      const user_manager::UserID user_id(user_manager::UserID::FromUserEmail(email));
       // Translate email to the display email.
-      std::string display_email = user_manager->GetUserDisplayEmail(email);
+      std::string display_email = user_manager->GetUserDisplayEmail(user_id);
       // TODO(ivankr): fetch display name for existing users.
-      user_list->Append(CreateUserInfo(email, display_email, std::string()));
+      user_list->Append(CreateUserInfo(user_id, display_email, std::string()));
     }
   }
   return user_list;
@@ -101,7 +102,7 @@ bool IsSecondaryUser(Profile* profile) {
   user_manager::UserManager* user_manager = user_manager::UserManager::Get();
   const user_manager::User* user =
       ProfileHelper::Get()->GetUserByProfile(profile);
-  return user && user->email() != user_manager->GetPrimaryUser()->email();
+  return user && user->GetUserID() != user_manager->GetPrimaryUser()->GetUserID();
 }
 
 const char kSelectNetworkMessage[] = "selectNetwork";
@@ -325,7 +326,7 @@ void CoreChromeOSOptionsHandler::GetLocalizedValues(
   user_manager::UserManager* user_manager = user_manager::UserManager::Get();
 
   if (IsSecondaryUser(profile)) {
-    const std::string& primary_email = user_manager->GetPrimaryUser()->email();
+    const std::string& primary_email = user_manager->GetPrimaryUser()->GetUserID().GetUserEmail();
 
     // Set secondaryUser to show the shared icon by the network section header.
     localized_strings->SetBoolean("secondaryUser", true);
@@ -362,7 +363,7 @@ void CoreChromeOSOptionsHandler::GetLocalizedValues(
     localized_strings->SetString("controlledSettingOwner",
         l10n_util::GetStringFUTF16(
             IDS_OPTIONS_CONTROLLED_SETTING_OWNER,
-            base::ASCIIToUTF16(user_manager->GetOwnerEmail())));
+            base::ASCIIToUTF16(user_manager->GetOwnerID().GetUserEmail())));
   }
 }