Issue #1830848 by mtunay: Convert the 'translation_language_type()' variable to CMI.

core/modules/translation/config/translation.settings.yml

@@ -0,0 +1 @@
+language_type: "language_interface"

core/modules/translation/translation.install

@@ -15,3 +15,14 @@ function translation_update_8000() {
     ->condition('permission', 'translate content')
     ->execute();
 }
+
+/**
+* Moves "translation_language_type" from variable to config.
+*
+* @ingroup config_upgrade
+ */
+function translation_update_8001() {
+  update_variables_to_config('translation.settings', array(
+    'translation_language_type' => 'language_type',
+  ));
+}

core/modules/translation/translation.module

@@ -259,7 +259,7 @@ function translation_node_view(Node $node, $view_mode) {
     // only for configurable language types and interface language is the only
     // configurable language type in core, we use it as default. Contributed
     // modules can change this behavior by setting the system variable below.
-    $type = variable_get('translation_language_type', LANGUAGE_TYPE_INTERFACE);
+    $type = config('translation.settings')->get('language_type');
     $custom_links = language_negotiation_get_switch_links($type, "node/$node->nid");
     $links = array();
 
@@ -537,8 +537,7 @@ function translation_path_get_translations($path) {
  * Replaces links with pointers to translated versions of the content.
  */
 function translation_language_switch_links_alter(array &$links, $type, $path) {
-  $language_type = variable_get('translation_language_type', LANGUAGE_TYPE_INTERFACE);
-
+  $language_type = config('translation.settings')->get('language_type');
   if ($type == $language_type && preg_match("!^node/(\d+)(/.+|)!", $path, $matches)) {
     $node = node_load((int) $matches[1]);
 

core/modules/translation/translation.pages.inc

@@ -32,7 +32,7 @@ function translation_node_overview(Node $node) {
     $translations = array($node->langcode => $node);
   }
 
-  $type = variable_get('translation_language_type', LANGUAGE_TYPE_INTERFACE);
+  $type = config('translation.settings')->get('language_type');
   $header = array(t('Language'), t('Title'), t('Status'), t('Operations'));
 
   foreach (language_list() as $langcode => $language) {