Clear the access token when destroying the Sync backend

chrome/browser/sync/profile_sync_service.cc

 // Copyright (c) 2012 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 <cstddef>
 #include <map>
 #include <set>
 #include <utility>
@@ skipping 798 matching lines @@
   UMA_HISTOGRAM_TIMES("Sync.Shutdown.BackendDestroyedTime", shutdown_time);
 
   weak_factory_.InvalidateWeakPtrs();
 
   // Clear various flags.
   start_up_time_ = base::Time();
   expect_sync_configuration_aborted_ = false;
   is_auth_in_progress_ = false;
   backend_initialized_ = false;
   cached_passphrase_.clear();
+  access_token_.clear();
   encryption_pending_ = false;
   encrypt_everything_ = false;
   encrypted_types_ = syncer::SyncEncryptionHandler::SensitiveTypes();
   passphrase_required_reason_ = syncer::REASON_PASSPHRASE_NOT_REQUIRED;
   request_access_token_retry_timer_.Stop();
   // Revert to "no auth error".
   if (last_auth_error_.state() != GoogleServiceAuthError::NONE)
     UpdateAuthErrorState(GoogleServiceAuthError::AuthErrorNone());
 
   if (sync_global_error_) {
@@ skipping 1336 matching lines @@
     NOTREACHED();
 #endif
   }
 
   return signin_->GetAuthenticatedUsername();
 }
 
 WeakHandle<syncer::JsEventHandler> ProfileSyncService::GetJsEventHandler() {
   return MakeWeakHandle(sync_js_controller_.AsWeakPtr());
 }