[Sync] USS: Fix race condition in DeviceInfoService + add error handling

sync/internal_api/shared_model_type_processor.cc

Index: sync/internal_api/shared_model_type_processor.cc
diff --git a/sync/internal_api/shared_model_type_processor.cc b/sync/internal_api/shared_model_type_processor.cc
index b2f34d019093639ca3069f039824a564a95cea71..8b046240dabaa0a8df7a2e3c8b452994ae202256 100644
--- a/sync/internal_api/shared_model_type_processor.cc
+++ b/sync/internal_api/shared_model_type_processor.cc
@@ -200,6 +200,17 @@ void SharedModelTypeProcessor::DisableSync() {
   service_->ApplySyncChanges(std::move(change_list), EntityChangeList());
 }
 
+syncer::SyncError SharedModelTypeProcessor::CreateAndUploadError(
+    const tracked_objects::Location& location,
+    const std::string& message) {
+  if (error_handler_) {
+    return error_handler_->CreateAndUploadError(location, message, type_);
+  } else {
+    return syncer::SyncError(location, syncer::SyncError::DATATYPE_ERROR,
+                             message, type_);
+  }
+}
+
 void SharedModelTypeProcessor::ConnectSync(
     std::unique_ptr<CommitQueue> worker) {
   DCHECK(CalledOnValidThread());