Task Scheduler API migration: change BrowserThreadModelWorker to SequencedModelWorker

ios/chrome/browser/sync/ios_chrome_sync_client.mm

Index: ios/chrome/browser/sync/ios_chrome_sync_client.mm
diff --git a/ios/chrome/browser/sync/ios_chrome_sync_client.mm b/ios/chrome/browser/sync/ios_chrome_sync_client.mm
index cc349d6ebdc546e90731e355ee703cdc5c977bd5..d066897389a38fff3855629d0161ffba49403250 100644
--- a/ios/chrome/browser/sync/ios_chrome_sync_client.mm
+++ b/ios/chrome/browser/sync/ios_chrome_sync_client.mm
@@ -35,8 +35,8 @@
 #include "components/sync/base/report_unrecoverable_error.h"
 #include "components/sync/driver/sync_api_component_factory.h"
 #include "components/sync/driver/sync_util.h"
-#include "components/sync/engine/browser_thread_model_worker.h"
 #include "components/sync/engine/passive_model_worker.h"
+#include "components/sync/engine/sequenced_model_worker.h"
 #include "components/sync/engine/ui_model_worker.h"
 #include "components/sync_preferences/pref_service_syncable.h"
 #include "components/sync_sessions/favicon_cache.h"
@@ -379,11 +379,11 @@ IOSChromeSyncClient::CreateModelWorkerForGroup(syncer::ModelSafeGroup group) {
   DCHECK_CURRENTLY_ON(web::WebThread::UI);
   switch (group) {
     case syncer::GROUP_DB:
-      return new syncer::BrowserThreadModelWorker(
+      return new syncer::SequencedModelWorker(
           web::WebThread::GetTaskRunnerForThread(web::WebThread::DB),
           syncer::GROUP_DB);
     case syncer::GROUP_FILE:
-      return new syncer::BrowserThreadModelWorker(
+      return new syncer::SequencedModelWorker(
           web::WebThread::GetTaskRunnerForThread(web::WebThread::FILE),
           syncer::GROUP_FILE);
     case syncer::GROUP_UI: