message: Some more small cleanup
diff: @@ -913,7 +913,8 @@ bool IndexMain_DoCreateIndexUpdate(
  return false;
  Timer time;
  - IndexUpdate update = IndexUpdate::CreateDelta(response->previous_id_map.get(), response->current_id_map.get(),
  + IndexUpdate update = IndexUpdate::CreateDelta(
  + response->previous_id_map.get(), response->current_id_map.get(),
  response->previous_index.get(), response->current_index.get());
  response->perf.index_make_delta = time.ElapsedMicrosecondsAndReset();
  @@ -2870,21 +2871,17 @@ bool QueryDbMainLoop(
  Timer time;
  assert(request->current);
  - std::shared_ptr<CacheManager::Entry> previous;
  - std::shared_ptr<CacheManager::Entry> current;
  - {
  - auto id_map = std::make_shared<IdMap>(db, request->current->id_cache);
  - std::shared_ptr<CacheManager::Entry> current0 =
  - std::make_shared<CacheManager::Entry>(std::move(request->current),
  - std::move(id_map));
  - current = current0;
  - previous = db_cache->UpdateAndReturnOldFile(std::move(current0));
  - }
  + // Build IdMap for the new instance. Replace the value in the cache.
  + auto id_map_current = std::make_shared<IdMap>(db, request->current->id_cache);
  + std::shared_ptr<CacheManager::Entry> current = std::make_shared<CacheManager::Entry>(request->current, id_map_current);
  + std::shared_ptr<CacheManager::Entry> previous = db_cache->UpdateAndReturnOldFile(current);
  + // Let response know about previous id map, if available.
  if (previous) {
  - response.previous_id_map = std::move(previous->ids);
  - response.previous_index = std::move(previous->file);
  + response.previous_id_map = previous->ids;
  + response.previous_index = previous->file;
  }
  + // Let response know about current id map, if available.
  response.current_id_map = current->ids;
  response.current_index = current->file;
  response.perf.querydb_id_map = time.ElapsedMicrosecondsAndReset();
  