Allow sync with 2-factor StrongAuth accounts in ChromeOS.

chrome/browser/sync/signin_manager.cc

 // Copyright (c) 2010 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/sync/signin_manager.h"
 
 #include "base/string_util.h"
 #include "chrome/browser/net/gaia/token_service.h"
 #include "chrome/browser/prefs/pref_service.h"
 #include "chrome/browser/profile.h"
@@ skipping 31 matching lines @@
 void SigninManager::SetUsername(const std::string& username) {
   username_ = username;
 }
 
 // Users must always sign out before they sign in again.
 void SigninManager::StartSignIn(const std::string& username,
                                 const std::string& password,
                                 const std::string& login_token,
                                 const std::string& login_captcha) {
   DCHECK(username_.empty());
+#if !defined(OS_CHROMEOS)
   // The Sign out should clear the token service credentials.
+  // Note: In CHROMEOS we might have valid credentials but still need to
+  // set up 2-factor authentication.
   DCHECK(!profile_->GetTokenService()->AreCredentialsValid());
-
+#endif
   username_.assign(username);
   password_.assign(password);
 
   client_login_.reset(new GaiaAuthFetcher(this,
                                           GaiaConstants::kChromeSource,
                                           profile_->GetRequestContext()));
   client_login_->StartClientLogin(username,
                                   password,
                                   "",
                                   login_token,
@@ skipping 84 matching lines @@
   bool invalid_gaia = error.state() ==
       GoogleServiceAuthError::INVALID_GAIA_CREDENTIALS;
   if (error.state() == GoogleServiceAuthError::TWO_FACTOR ||
       (had_two_factor_error_ && invalid_gaia)) {
     had_two_factor_error_ = true;
     return;
   }
 
   SignOut();
 }