This CL fixes the issue with login using alternative e-mails.

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

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "chrome/browser/ui/webui/chromeos/login/gaia_screen_handler.h"
 
 #include "ash/system/chromeos/devicetype_utils.h"
 #include "base/bind.h"
 #include "base/guid.h"
 #include "base/logging.h"
@@ skipping 462 matching lines @@
   else
     frame_error_ = net::ERR_INTERNET_DISCONNECTED;
 
   LOG(ERROR) << "Gaia webview error: " << error_reason_str;
   NetworkError::ErrorReason error_reason =
       NetworkError::ERROR_REASON_FRAME_ERROR;
   frame_state_ = FRAME_STATE_ERROR;
   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,
     const std::string& password,
     const std::string& auth_code,
     bool using_saml,
     const std::string& gaps_cookie) {
   if (!Delegate())
     return;
 
   DCHECK(!email.empty());
   DCHECK(!gaia_id.empty());
   const std::string sanitized_email = gaia::SanitizeEmail(email);
   Delegate()->SetDisplayEmail(sanitized_email);
-  UserContext user_context(sanitized_email);
+
+  const std::string canonical_email = GetCanonicalEmail(email, gaia_id);
+  UserContext user_context(canonical_email);
   user_context.SetGaiaID(gaia_id);
   user_context.SetKey(Key(password));
   user_context.SetAuthCode(auth_code);
   user_context.SetAuthFlow(using_saml
                                ? UserContext::AUTH_FLOW_GAIA_WITH_SAML
                                : UserContext::AUTH_FLOW_GAIA_WITHOUT_SAML);
   user_context.SetGAPSCookie(gaps_cookie);
   Delegate()->CompleteLogin(user_context);
 }
 
@@ skipping 100 matching lines @@
   if (!Delegate())
     return;
 
   if (using_saml && !using_saml_api_)
     RecordSAMLScrapingVerificationResultInHistogram(true);
 
   DCHECK(!typed_email.empty());
   DCHECK(!gaia_id.empty());
   const std::string sanitized_email = gaia::SanitizeEmail(typed_email);
   Delegate()->SetDisplayEmail(sanitized_email);
-  UserContext user_context(sanitized_email);
+  const std::string canonical_email = GetCanonicalEmail(typed_email, gaia_id);
+  UserContext user_context(canonical_email);
   user_context.SetGaiaID(gaia_id);
   user_context.SetKey(Key(password));
   user_context.SetAuthFlow(using_saml
                                ? UserContext::AUTH_FLOW_GAIA_WITH_SAML
                                : UserContext::AUTH_FLOW_GAIA_WITHOUT_SAML);
   Delegate()->CompleteLogin(user_context);
 
   if (test_expects_complete_login_) {
     VLOG(2) << "Complete test login for " << typed_email
             << ", requested=" << test_user_;
@@ skipping 257 matching lines @@
 SigninScreenHandlerDelegate* GaiaScreenHandler::Delegate() {
   return signin_screen_handler_->delegate_;
 }
 
 bool GaiaScreenHandler::IsRestrictiveProxy() const {
   return captive_portal_status_ ==
          NetworkPortalDetector::CAPTIVE_PORTAL_STATUS_PORTAL;
 }
 
 }  // namespace chromeos