drupal/core/modules/content_translation/content_translation.install

<?php

/**
 * @file
 * Installation functions for Content Translation module.
 */

use \Drupal\Core\Url;

/**
 * Implements hook_install().
 */
function content_translation_install() {
  // Assign a fairly low weight to ensure our implementation of
  // hook_module_implements_alter() is run among the last ones.
  module_set_weight('content_translation', 10);
  // Translation works when at least two languages are added.
  if (count(\Drupal::languageManager()->getLanguages()) < 2) {
    // @todo: Switch to Url::fromRoute() once https://www.drupal.org/node/2589967 is resolved.
    $t_args = [':language_url' => Url::fromUri('internal:/admin/config/regional/language')->toString()];
    $message = t('This site has only a single language enabled. <a href=":language_url">Add at least one more language</a> in order to translate content.', $t_args);
    drupal_set_message($message, 'warning');
  }
  // Point the user to the content translation settings.
  $t_args = [':settings_url' => Url::fromUri('internal:/admin/config/regional/content-language')->toString()];
  $message = t('<a href=":settings_url">Enable translation</a> for <em>content types</em>, <em>taxonomy vocabularies</em>, <em>accounts</em>, or any other element you wish to translate.', $t_args);
  drupal_set_message($message, 'warning');
}

/**
 * @addtogroup updates-8.0.0-rc
 * @{
 */

/**
 * Rebuild the routes as the content translation routes have now new names.
 */
function content_translation_update_8001() {
  \Drupal::service('router.builder')->rebuild();
}

/**
 * @} End of "addtogroup updates-8.0.0-rc".
 */

/**
 * @addtogroup updates-8.0.x
 * @{
 */

/**
 * Clear field type plugin caches to fix image field translatability.
 */
function content_translation_update_8002() {
  \Drupal::service('plugin.manager.field.field_type')->clearCachedDefinitions();
}

/**
 * @} End of "addtogroup updates-8.0.x".
 */