[Sync] Sync client should to exponential backoff when receive partial failure

components/sync/engine_impl/sync_manager_impl.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 "components/sync/engine_impl/sync_manager_impl.h"
 
 #include <stddef.h>
 
 #include <utility>
 
@@ skipping 837 matching lines @@
 void SyncManagerImpl::OnActionableError(const SyncProtocolError& error) {
   for (auto& observer : observers_) {
     observer.OnActionableError(error);
   }
 }
 
 void SyncManagerImpl::OnRetryTimeChanged(base::Time) {}
 
 void SyncManagerImpl::OnThrottledTypesChanged(ModelTypeSet) {}
 
+void SyncManagerImpl::OnBackedOffTypesChanged(ModelTypeSet) {}
+
 void SyncManagerImpl::OnMigrationRequested(ModelTypeSet types) {
   for (auto& observer : observers_) {
     observer.OnMigrationRequested(types);
   }
 }
 
 void SyncManagerImpl::OnProtocolEvent(const ProtocolEvent& event) {
   protocol_event_buffer_.RecordProtocolEvent(event);
   for (auto& observer : observers_) {
     observer.OnProtocolEvent(event);
@@ skipping 144 matching lines @@
 }
 
 void SyncManagerImpl::OnCookieJarChanged(bool account_mismatch,
                                          bool empty_jar) {
   DCHECK(thread_checker_.CalledOnValidThread());
   cycle_context_->set_cookie_jar_mismatch(account_mismatch);
   cycle_context_->set_cookie_jar_empty(empty_jar);
 }
 
 }  // namespace syncer