constructor() {
    /**
     * Per-log information retained by this LogRegistry_.
     * @type {!Object<string, !goog.log.LogRegistryEntry_>}
     */
    this.entries = {};

    // The root logger.
    const rootLogRegistryEntry =
        new goog.log.LogRegistryEntry_(goog.log.ROOT_LOGGER_NAME);
    rootLogRegistryEntry.level = goog.log.Level.CONFIG;
    this.entries[goog.log.ROOT_LOGGER_NAME] = rootLogRegistryEntry;
  }
A LogRegistry_ owns references to all loggers, and is responsible for storing
all the internal state needed for loggers to operate correctly.

@final