code: function updateFromDownload(installationResult) {
          if (installationResult.keepFile === undefined) {
              installationResult.keepFile = false;
          }
  
          var installationStatus = installationResult.installationStatus;
          if (installationStatus === Package.InstallationStatuses.ALREADY_INSTALLED ||
                  installationStatus === Package.InstallationStatuses.NEEDS_UPDATE ||
                  installationStatus === Package.InstallationStatuses.SAME_VERSION ||
                  installationStatus === Package.InstallationStatuses.OLDER_VERSION) {
              var id = installationResult.name;
              delete _idsToRemove[id];
              _idsToUpdate[id] = installationResult;
              exports.trigger("statusChange", id);
          }
      }
docs: If a downloaded package appears to be an update, mark the extension for update.
  If an extension was previously marked for removal, marking for update will
  turn off the removal mark.
  @param {Object} installationResult info about the install provided by the Package.download function