DCHECK that ProfileSyncService is created on the UI thread.

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 <vector>
 
@@ skipping 224 matching lines @@
       connection_status_(syncer::CONNECTION_NOT_ATTEMPTED),
       last_get_token_error_(GoogleServiceAuthError::AuthErrorNone()),
       network_resources_(new syncer::HttpBridgeNetworkResources),
       backend_mode_(IDLE),
       need_backup_(false),
       backup_finished_(false),
       clear_browsing_data_(base::Bind(&ClearBrowsingData)),
       browsing_data_remover_observer_(NULL),
       weak_factory_(this),
       startup_controller_weak_factory_(this) {
+  DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   DCHECK(profile);
   startup_controller_.reset(new browser_sync::StartupController(
       start_behavior,
       oauth2_token_service,
       &sync_prefs_,
       signin_.get(),
       base::Bind(&ProfileSyncService::StartUpSlowBackendComponents,
                  startup_controller_weak_factory_.GetWeakPtr(),
                  SYNC)));
   backup_rollback_controller_.reset(new browser_sync::BackupRollbackController(
@@ skipping 2489 matching lines @@
 
 base::MessageLoop* ProfileSyncService::GetSyncLoopForTest() const {
   if (sync_thread_) {
     return sync_thread_->message_loop();
   } else if (backend_) {
     return backend_->GetSyncLoopForTesting();
   } else {
     return NULL;
   }
 }