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

chromeos/login/auth/extended_authenticator_impl.cc

Index: chromeos/login/auth/extended_authenticator_impl.cc
diff --git a/chromeos/login/auth/extended_authenticator_impl.cc b/chromeos/login/auth/extended_authenticator_impl.cc
index 0aa10e59b76fac6235366d3ec576feba59c0677f..a200a764b6446708563cea1786a7a83f348fdcb0 100644
--- a/chromeos/login/auth/extended_authenticator_impl.cc
+++ b/chromeos/login/auth/extended_authenticator_impl.cc
@@ -79,13 +79,12 @@ void ExtendedAuthenticatorImpl::AuthenticateToCheck(
 }
 
 void ExtendedAuthenticatorImpl::CreateMount(
-    const std::string& user_id,
+    const user_manager::UserID& user_id,
     const std::vector<cryptohome::KeyDefinition>& keys,
     const ResultCallback& success_callback) {
   RecordStartMarker("MountEx");
 
-  std::string canonicalized = gaia::CanonicalizeEmail(user_id);
-  cryptohome::Identification id(canonicalized);
+  cryptohome::Identification id(user_id);
   cryptohome::Authorization auth(keys.front());
   cryptohome::MountParameters mount(false);
   for (size_t i = 0; i < keys.size(); i++) {
@@ -186,8 +185,7 @@ void ExtendedAuthenticatorImpl::DoAuthenticateToMount(
     const UserContext& user_context) {
   RecordStartMarker("MountEx");
 
-  std::string canonicalized = gaia::CanonicalizeEmail(user_context.GetUserID());
-  cryptohome::Identification id(canonicalized);
+  cryptohome::Identification id(user_context.GetUserID());
   const Key* const key = user_context.GetKey();
   cryptohome::Authorization auth(key->GetSecret(), key->GetLabel());
   cryptohome::MountParameters mount(false);
@@ -208,8 +206,7 @@ void ExtendedAuthenticatorImpl::DoAuthenticateToCheck(
     const UserContext& user_context) {
   RecordStartMarker("CheckKeyEx");
 
-  std::string canonicalized = gaia::CanonicalizeEmail(user_context.GetUserID());
-  cryptohome::Identification id(canonicalized);
+  cryptohome::Identification id(user_context.GetUserID());
   const Key* const key = user_context.GetKey();
   cryptohome::Authorization auth(key->GetSecret(), key->GetLabel());
 
@@ -229,8 +226,7 @@ void ExtendedAuthenticatorImpl::DoAddKey(const cryptohome::KeyDefinition& key,
                                      const UserContext& user_context) {
   RecordStartMarker("AddKeyEx");
 
-  std::string canonicalized = gaia::CanonicalizeEmail(user_context.GetUserID());
-  cryptohome::Identification id(canonicalized);
+  cryptohome::Identification id(user_context.GetUserID());
   const Key* const auth_key = user_context.GetKey();
   cryptohome::Authorization auth(auth_key->GetSecret(), auth_key->GetLabel());
 
@@ -253,8 +249,7 @@ void ExtendedAuthenticatorImpl::DoUpdateKeyAuthorized(
     const UserContext& user_context) {
   RecordStartMarker("UpdateKeyAuthorized");
 
-  std::string canonicalized = gaia::CanonicalizeEmail(user_context.GetUserID());
-  cryptohome::Identification id(canonicalized);
+  cryptohome::Identification id(user_context.GetUserID());
   const Key* const auth_key = user_context.GetKey();
   cryptohome::Authorization auth(auth_key->GetSecret(), auth_key->GetLabel());
 
@@ -275,8 +270,7 @@ void ExtendedAuthenticatorImpl::DoRemoveKey(const std::string& key_to_remove,
                                         const UserContext& user_context) {
   RecordStartMarker("RemoveKeyEx");
 
-  std::string canonicalized = gaia::CanonicalizeEmail(user_context.GetUserID());
-  cryptohome::Identification id(canonicalized);
+  cryptohome::Identification id(user_context.GetUserID());
   const Key* const auth_key = user_context.GetKey();
   cryptohome::Authorization auth(auth_key->GetSecret(), auth_key->GetLabel());