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

chrome/browser/ui/webui/help/help_handler.cc

Index: chrome/browser/ui/webui/help/help_handler.cc
diff --git a/chrome/browser/ui/webui/help/help_handler.cc b/chrome/browser/ui/webui/help/help_handler.cc
index 193c960b7430a617f000a9b7982c5fc79254b61a..482fed4d7ba79315c6d38d8b3e2dfabbdc44aa13 100644
--- a/chrome/browser/ui/webui/help/help_handler.cc
+++ b/chrome/browser/ui/webui/help/help_handler.cc
@@ -108,7 +108,7 @@ bool CanChangeChannel(Profile* profile) {
     const user_manager::User* user =
         profile ? chromeos::ProfileHelper::Get()->GetUserByProfile(profile)
                 : nullptr;
-    std::string email = user ? user->email() : std::string();
+    std::string email = user ? user->GetUserID().GetUserEmail() : std::string();
     size_t at_pos = email.find('@');
     if (at_pos != std::string::npos && at_pos + 1 < email.length())
       domain = email.substr(email.find('@') + 1);