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

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

Index: chrome/browser/chromeos/login/easy_unlock/easy_unlock_tpm_key_manager_factory.cc
diff --git a/chrome/browser/chromeos/login/easy_unlock/easy_unlock_tpm_key_manager_factory.cc b/chrome/browser/chromeos/login/easy_unlock/easy_unlock_tpm_key_manager_factory.cc
index c12f2fbe7f507dbeee13f83de592f17b0336db20..925d1e5e5a34df360cd3c42c258ed557de7de729 100644
--- a/chrome/browser/chromeos/login/easy_unlock/easy_unlock_tpm_key_manager_factory.cc
+++ b/chrome/browser/chromeos/login/easy_unlock/easy_unlock_tpm_key_manager_factory.cc
@@ -35,7 +35,7 @@ EasyUnlockTpmKeyManager* EasyUnlockTpmKeyManagerFactory::Get(
 }
 
 EasyUnlockTpmKeyManager* EasyUnlockTpmKeyManagerFactory::GetForUser(
-    const std::string& user_id) {
+    const user_manager::UserID& user_id) {
   const user_manager::User* user =
       user_manager::UserManager::Get()->FindUser(user_id);
   if (!user)
@@ -62,7 +62,7 @@ KeyedService* EasyUnlockTpmKeyManagerFactory::BuildServiceInstanceFor(
   if (!chromeos::ProfileHelper::IsSigninProfile(profile))
     user = chromeos::ProfileHelper::Get()->GetUserByProfile(profile);
   return new EasyUnlockTpmKeyManager(
-      user ? user->email() : std::string(),
+      user ? user->GetUserID() : user_manager::UserID(std::string(), std::string()),

[Denis Kuznetsov (DE-MUC), 2015/06/10 16:50:45]

EmptyUserID()

       user ? user->username_hash() : std::string(), GetLocalState());
 }