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

ash/test/test_session_state_delegate.cc

Index: ash/test/test_session_state_delegate.cc
diff --git a/ash/test/test_session_state_delegate.cc b/ash/test/test_session_state_delegate.cc
index a2b99c85521b6e4f2c5aab47eeff236d8d2d888d..0c2e5da182f44d556f5b40798a6623136de27851 100644
--- a/ash/test/test_session_state_delegate.cc
+++ b/ash/test/test_session_state_delegate.cc
@@ -231,9 +231,9 @@ bool TestSessionStateDelegate::ShouldShowAvatar(aura::Window* window) const {
   return !GetActiveUserInfo()->GetImage().isNull();
 }
 
-void TestSessionStateDelegate::SwitchActiveUser(const std::string& user_id) {
+void TestSessionStateDelegate::SwitchActiveUser(const user_manager::UserID& user_id) {
   // Make sure this is a user id and not an email address.
-  EXPECT_EQ(user_id, GetUserIDFromEmail(user_id));
+  EXPECT_EQ(user_id.GetUserEmail(), GetUserIDFromEmail(user_id.GetUserEmail()));

[Denis Kuznetsov (DE-MUC), 2015/06/10 16:50:46]

No need for this check here. This check should be done at UserID creation time.

   active_user_index_ = 0;
   for (std::vector<MockUserInfo*>::iterator iter = user_list_.begin();
        iter != user_list_.end();
@@ -247,7 +247,7 @@ void TestSessionStateDelegate::SwitchActiveUser(const std::string& user_id) {
 }
 
 void TestSessionStateDelegate::CycleActiveUser(CycleUser cycle_user) {
-  SwitchActiveUser("someone@tray");
+  SwitchActiveUser(user_manager::UserID(std::string(), "someone@tray"));

[Denis Kuznetsov (DE-MUC), 2015/06/10 16:50:46]

FromUserEmail()

 }
 
 bool TestSessionStateDelegate::IsMultiProfileAllowedByPrimaryUserPolicy()