Revert of ChromeOS: fix user signin by alias.

chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc

Index: chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
diff --git a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
index 4430ce36e5adff5fa51fb9b6663039a537f26cd0..34c61120f6cc61fb28641bd50aa29d52c23725ff 100644
--- a/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
+++ b/chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.cc
@@ -515,29 +515,6 @@
   UpdateState(error_reason);
 }
 
-std::string GaiaScreenHandler::GetCanonicalEmail(
-    const std::string& authenticated_email,
-    const std::string& gaia_id) const {
-  const std::string sanitized_email = gaia::SanitizeEmail(authenticated_email);
-
-  const std::string canonicalized_email =
-      gaia::CanonicalizeEmail(sanitized_email);
-  user_manager::UserManager* user_manager = user_manager::UserManager::Get();
-  if (user_manager && !user_manager->IsKnownUser(canonicalized_email)) {
-    std::string old_canonical_email;
-    if (user_manager->GetKnownUserCanonicalEmail(gaia_id,
-                                                 &old_canonical_email)) {
-      if (old_canonical_email != canonicalized_email) {
-        LOG(WARNING) << "Existing user '" << old_canonical_email
-                     << "' authenticated by alias '" << sanitized_email << "'.";
-        return old_canonical_email;
-      }
-    }
-  }
-  // For compatibility reasons, sanitized email is used.
-  return sanitized_email;
-}
-
 void GaiaScreenHandler::HandleCompleteAuthentication(
     const std::string& gaia_id,
     const std::string& email,
@@ -554,9 +531,7 @@
   DCHECK(!gaia_id.empty());
   const std::string sanitized_email = gaia::SanitizeEmail(email);
   Delegate()->SetDisplayEmail(sanitized_email);
-
-  const std::string canonical_email = GetCanonicalEmail(email, gaia_id);
-  UserContext user_context(canonical_email);
+  UserContext user_context(sanitized_email);
   user_context.SetGaiaID(gaia_id);
   user_context.SetKey(Key(password));
   user_context.SetAuthCode(auth_code);
@@ -682,8 +657,7 @@
   DCHECK(!gaia_id.empty());
   const std::string sanitized_email = gaia::SanitizeEmail(typed_email);
   Delegate()->SetDisplayEmail(sanitized_email);
-  const std::string canonical_email = GetCanonicalEmail(typed_email, gaia_id);
-  UserContext user_context(canonical_email);
+  UserContext user_context(sanitized_email);
   user_context.SetGaiaID(gaia_id);
   user_context.SetKey(Key(password));
   user_context.SetAuthFlow(using_saml