code: function rezip(contentsZip) {
    return preprocessToRezip(contentsZip).then(
      ({ zipFile, entries, manifestJson, manifestPath }) => {
        validateManifest(entries, manifestJson, manifestPath);
        return rezipContents(zipFile, entries, manifestJson, manifestPath);
      }
    );
  }
docs: Extract, validate and rezip contents.zip
  
  @param {!Buffer} contentsZip The zipped plugin contents directory.
  @return {!Promise<!Buffer>}