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

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

 // 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.
 
 #ifndef CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_GAIA_SCREEN_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_GAIA_SCREEN_HANDLER_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 199 matching lines @@
   bool IsRestrictiveProxy() const;
 
   SigninScreenHandlerDelegate* Delegate();
 
   // Returns temporary unused device Id.
   std::string GetTemporaryDeviceId();
 
   FrameState frame_state() const { return frame_state_; }
   net::Error frame_error() const { return frame_error_; }
 
+  // Returns user canonical e-mail. Finds already used account alias, if
+  // user has already signed in.
+  std::string GetCanonicalEmail(const std::string& authenticated_email,
+                                const std::string& gaia_id) const;
+
   // Current state of Gaia frame.
   FrameState frame_state_ = FRAME_STATE_UNKNOWN;
 
   // Latest Gaia frame error.
   net::Error frame_error_ = net::OK;
 
   // Network state informer used to keep signin screen up.
   scoped_refptr<NetworkStateInformer> network_state_informer_;
 
   // Consumer management service for checking if enrollment is in progress.
@@ skipping 54 matching lines @@
   scoped_ptr<ScopedGaiaAuthExtension> auth_extension_;
 
   base::WeakPtrFactory<GaiaScreenHandler> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(GaiaScreenHandler);
 };
 
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_UI_WEBUI_CHROMEOS_LOGIN_GAIA_SCREEN_HANDLER_H_