Do not clear tokens from db when the user enters new credentials.

chrome/browser/sync/profile_sync_service.cc

 // Copyright (c) 2011 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/profile_sync_service.h"
 
 #include <algorithm>
 #include <cstddef>
 #include <map>
 #include <set>
@@ skipping 1058 matching lines @@
     // two factor signin), so initialize signin_ here.
     signin_->Initialize(profile_);
   }
 
   if (!access_code.empty()) {
     signin_->ProvideSecondFactorAccessCode(access_code);
     return;
   }
 
   if (!signin_->GetUsername().empty()) {
-    signin_->SignOut();
+    signin_->ClearInMemoryData();
   }
 
   // The user has submitted credentials, which indicates they don't
   // want to suppress start up anymore.
   sync_prefs_.SetStartSuppressed(false);
 
   signin_->StartSignIn(username,
                        password,
                        last_auth_error_.captcha().token,
                        captcha);
@@ skipping 465 matching lines @@
             << "Unrecoverable error.";
   } else {
     VLOG(0) << "ConfigureDataTypeManager not invoked because backend is not "
             << "initialized";
   }
 }
 
 const FailedDatatypesHandler& ProfileSyncService::failed_datatypes_handler() {
   return failed_datatypes_handler_;
 }