diff --git a/core/modules/locale/lib/Drupal/locale/Gettext.php b/core/modules/locale/lib/Drupal/locale/Gettext.php
index b21023a..40472f0 100644
--- a/core/modules/locale/lib/Drupal/locale/Gettext.php
+++ b/core/modules/locale/lib/Drupal/locale/Gettext.php
@@ -53,7 +53,7 @@ static function filesToArray($langcode, array $files) {
    *
    * @param stdClass $file
    *   File object with an URI property pointing at the file's path.
-   *   - "langcode": The language the language the strings will be added to.
+   *   - "langcode": The language the strings will be added to.
    *   - "uri": File URI.
    * @param array $options
    *   An array with options that can have the following elements:
diff --git a/core/modules/locale/lib/Drupal/locale/Tests/LocaleUpdateTest.php b/core/modules/locale/lib/Drupal/locale/Tests/LocaleUpdateTest.php
index 07a1887..b7d3d50 100644
--- a/core/modules/locale/lib/Drupal/locale/Tests/LocaleUpdateTest.php
+++ b/core/modules/locale/lib/Drupal/locale/Tests/LocaleUpdateTest.php
@@ -58,7 +58,7 @@ public static function getInfo() {
   }
 
   /**
-   * Setup the test environment.
+   * Set up the test environment.
    *
    * We use German as default test language. Due to hardcoded configurations in
    * the locale_test module, the language can not be chosen randomly.
@@ -71,7 +71,7 @@ function setUp() {
     $this->drupalLogin($admin_user);
     $this->drupalPost('admin/config/regional/language/add', array('predefined_langcode' => 'de'), t('Add language'));
 
-    // Setup timestamps to identify old and new translation sources.
+    // Set up timestamps to identify old and new translation sources.
     $this->timestamp_old = REQUEST_TIME - 300;
     $this->timestamp_medium = REQUEST_TIME - 200;
     $this->timestamp_new = REQUEST_TIME - 100;
@@ -79,7 +79,7 @@ function setUp() {
   }
 
   /**
-   * Set the value of the default translations directory.
+   * Sets the value of the default translations directory.
    *
    * @param string $path
    *   Path of the translations directory relative to the drupal installation
@@ -92,7 +92,7 @@ private function setTranslationsDirectory($path) {
   }
 
   /**
-   * Add a language.
+   * Adds a language.
    *
    * @param $langcode
    *   The language code of the language to add.
@@ -115,7 +115,8 @@ function addLanguage($langcode) {
    *   Timestamp to set the file to. Defaults to current time.
    * @param array $translations
    *   Array of source/target value translation strings. Only singular strings
-   *   are supported, no plurals.
+   *   are supported, no plurals. No double quotes are allowed in source and
+   *   translations strings.
    */
   private function makePoFile($path, $filename, $timestamp = NULL, $translations = array()) {
     $timestamp = $timestamp ? $timestamp : REQUEST_TIME;
@@ -155,7 +156,7 @@ private function makePoFile($path, $filename, $timestamp = NULL, $translations =
   }
 
   /**
-   * Setup the environment containting local and remote translation files.
+   * Set up the environment containting local and remote translation files.
    *
    * Update tests require a simulated environment for local and remote files.
    * Normally remote files are located at a remote server (e.g. ftp.drupal.org).
@@ -216,7 +217,7 @@ private function setTranslationFiles() {
   }
 
   /**
-   * Setup existing translations in the database and setup the status of
+   * Set up existing translations in the database and set up the status of
    * existing translations.
    */
   private function setCurrentTranslations() {
@@ -227,7 +228,6 @@ private function setCurrentTranslations() {
       'March' => 'Marz',
       'June' => 'Juni',
     );
-    $customized = 0;
     foreach ($non_customized_translations as $source => $translation) {
       $string = locale_storage()->createString(array('source' => $source, 'context' => $context))
         ->save();
@@ -235,7 +235,7 @@ private function setCurrentTranslations() {
         'lid' => $string->getId(),
         'language' => $langcode,
         'translation' => $translation,
-        'customized' => $customized,
+        'customized' => LOCALE_NOT_CUSTOMIZED,
       ))->save();
     }
 
@@ -245,7 +245,6 @@ private function setCurrentTranslations() {
       'February' => 'Februar_customized',
       'May' => 'Mai_customized',
     );
-    $customized = 1;
     foreach ($customized_translations as $source => $translation) {
       $string = locale_storage()->createString(array('source' => $source, 'context' => $context))
         ->save();
@@ -253,7 +252,7 @@ private function setCurrentTranslations() {
         'lid' => $string->getId(),
         'language' => $langcode,
         'translation' => $translation,
-        'customized' => $customized,
+        'customized' => LOCALE_CUSTOMIZED,
       ))->save();
     }
 
@@ -291,35 +290,38 @@ private function setCurrentTranslations() {
   }
 
   /**
-   * Check the translation of an array of strings.
+   * Checks the translation of a string.
    *
    * @param string $source
    *   Translation source string
    * @param string $translation
    *   Translation to check. Use empty string to check for a not existing
    *   translation.
-   * @param $langcode
+   * @param string $langcode
    *   Language code of the language to translate to.
+   * @param string $message
+   *   (optional) A message to display with the assertion.
    */
   function assertTranslation($source, $translation, $langcode, $message = '') {
     $db_translation = db_query('SELECT translation FROM {locales_target} lt INNER JOIN {locales_source} ls ON ls.lid = lt.lid WHERE ls.source = :source AND lt.language = :langcode', array(':source' => $source, ':langcode' => $langcode))->fetchField();
-    $this->assertEqual((string) $translation, (string) $db_translation, $message ? $message : format_string('Correct translation of %source (%language)', array('%source' => $source, '%language' => $langcode)));
+    $db_translation = $db_translation == FALSE ? '' : $db_translation;
+    $this->assertEqual($translation, $db_translation, $message ? $message : format_string('Correct translation of %source (%language)', array('%source' => $source, '%language' => $langcode)));
   }
 
   /**
-   * Check if a list of translatable projects gets build.
+   * Checks if a list of translatable projects gets build.
    */
   function testUpdateProjects() {
     module_load_include('compare.inc', 'locale');
 
     // Make the test modules look like a normal custom module. i.e. make the
     // modules not hidden. locale_test_system_info_alter() modifies the project
-    // info of the locale_test and locale_test_disabled modules.
+    // info of the locale_test and locale_test_translate modules.
     state()->set('locale.test_system_info_alter', TRUE);
 
     // Check if interface translation data is collected from hook_info.
     $projects = locale_translation_project_list();
-    $this->assertFalse(isset($projects['locale_test_disabled']), 'Hidden module not found');
+    $this->assertFalse(isset($projects['locale_test_translate']), 'Hidden module not found');
     $this->assertEqual($projects['locale_test']['info']['interface translation server pattern'], 'core/modules/locale/test/test.%language.po', 'Interface translation parameter found in project info.');
     $this->assertEqual($projects['locale_test']['name'] , 'locale_test', format_string('%key found in project info.', array('%key' => 'interface translation project')));
   }
@@ -341,7 +343,7 @@ function testUpdateProjectsHidden() {
     $this->drupalPost('admin/config/regional/translate/settings', $edit, t('Save configuration'));
 
     $projects = locale_translation_project_list();
-    $this->assertTrue(isset($projects['locale_test_disabled']), 'Disabled module found');
+    $this->assertTrue(isset($projects['locale_test_translate']), 'Disabled module found');
     $this->assertTrue(isset($projects['locale_test']), 'Enabled module found');
   }
 
@@ -350,20 +352,19 @@ function testUpdateProjectsHidden() {
    *
    * The translation status process by default checks the status of the
    * installed projects. For testing purpose a predefined set of modules with
-   * fixed file names and release versions is used. Using a
-   * hook_locale_translation_projects_alter implementation in the locale_test
-   * module this custom project definition is applied.
+   * fixed file names and release versions is used. This custom project
+   * definition is applied using a hook_locale_translation_projects_alter
+   * implementation in the locale_test module.
    *
    * This test generates a set of local and remote translation files in their
    * respective local and remote translation directory. The test checks whether
    * the most recent files are selected in the different check scenarios: check
-   * for local files only, check for remote files only, check for both local and
-   * remote files.
+   * for local files only, check for both local and remote files.
    */
   function testUpdateCheckStatus() {
     $config = config('locale.settings');
-    // A flag is set to let the locale_test module replace the project data with
-    // a set of test projects.
+    // Set a flag to let the locale_test module replace the project data with a
+    // set of test projects.
     state()->set('locale.test_projects_alter', TRUE);
 
     // Create local and remote translations files.
@@ -377,15 +378,14 @@ function testUpdateCheckStatus() {
     $this->drupalPost('admin/config/regional/translate/settings', $edit, t('Save configuration'));
 
     // Get status of translation sources at local file system.
-    $config->set('translation.use_source', LOCALE_TRANSLATION_USE_SOURCE_LOCAL)->save();
     $this->drupalGet('admin/reports/translations/check');
     $result = state()->get('locale.translation_status');
-    $this->assertEqual($result['contrib_module_one']['de']->type, 'local', 'Translation of contrib_module_one found');
+    $this->assertEqual($result['contrib_module_one']['de']->type, LOCALE_TRANSLATION_LOCAL, 'Translation of contrib_module_one found');
     $this->assertEqual($result['contrib_module_one']['de']->timestamp, $this->timestamp_old, 'Translation timestamp found');
-    $this->assertEqual($result['contrib_module_two']['de']->type, 'local', 'Translation of contrib_module_two found');
+    $this->assertEqual($result['contrib_module_two']['de']->type, LOCALE_TRANSLATION_LOCAL, 'Translation of contrib_module_two found');
     $this->assertEqual($result['contrib_module_two']['de']->timestamp, $this->timestamp_new, 'Translation timestamp found');
-    $this->assertEqual($result['locale_test']['de']->type, 'local', 'Translation of locale_test found');
-    $this->assertEqual($result['custom_module_one']['de']->type, 'local', 'Translation of custom_module_one found');
+    $this->assertEqual($result['locale_test']['de']->type, LOCALE_TRANSLATION_LOCAL, 'Translation of locale_test found');
+    $this->assertEqual($result['custom_module_one']['de']->type, LOCALE_TRANSLATION_LOCAL, 'Translation of custom_module_one found');
 
     // Set the test conditions.
     $edit = array(
@@ -398,16 +398,16 @@ function testUpdateCheckStatus() {
     $result = state()->get('locale.translation_status');
     $this->assertEqual($result['contrib_module_one']['de']->type, 'remote', 'Translation of contrib_module_one found');
     $this->assertEqual($result['contrib_module_one']['de']->timestamp, $this->timestamp_new, 'Translation timestamp found');
-    $this->assertEqual($result['contrib_module_two']['de']->type, 'local', 'Translation of contrib_module_two found');
+    $this->assertEqual($result['contrib_module_two']['de']->type, LOCALE_TRANSLATION_LOCAL, 'Translation of contrib_module_two found');
     $this->assertEqual($result['contrib_module_two']['de']->timestamp, $this->timestamp_new, 'Translation timestamp found');
-    $this->assertEqual($result['contrib_module_three']['de']->type, 'local', 'Translation of contrib_module_three found');
+    $this->assertEqual($result['contrib_module_three']['de']->type, LOCALE_TRANSLATION_LOCAL, 'Translation of contrib_module_three found');
     $this->assertEqual($result['contrib_module_three']['de']->timestamp, $this->timestamp_old, 'Translation timestamp found');
-    $this->assertEqual($result['locale_test']['de']->type, 'local', 'Translation of locale_test found');
-    $this->assertEqual($result['custom_module_one']['de']->type, 'local', 'Translation of custom_module_one found');
+    $this->assertEqual($result['locale_test']['de']->type, LOCALE_TRANSLATION_LOCAL, 'Translation of locale_test found');
+    $this->assertEqual($result['custom_module_one']['de']->type, LOCALE_TRANSLATION_LOCAL, 'Translation of custom_module_one found');
   }
 
   /**
-   * Test translation import from remote sources.
+   * Tests translation import from remote sources.
    *
    * Test conditions:
    *  - Source: remote and local files
@@ -435,9 +435,9 @@ function testUpdateImportSourceRemote() {
 
     // Check if the translation has been updated, using the status cache.
     $status = state()->get('locale.translation_status');
-    $this->assertEqual($status['contrib_module_one']['de']->type, 'current', 'Translation of contrib_module_one found');
-    $this->assertEqual($status['contrib_module_two']['de']->type, 'current', 'Translation of contrib_module_two found');
-    $this->assertEqual($status['contrib_module_three']['de']->type, 'current', 'Translation of contrib_module_three found');
+    $this->assertEqual($status['contrib_module_one']['de']->type, LOCALE_TRANSLATION_CURRENT, 'Translation of contrib_module_one found');
+    $this->assertEqual($status['contrib_module_two']['de']->type, LOCALE_TRANSLATION_CURRENT, 'Translation of contrib_module_two found');
+    $this->assertEqual($status['contrib_module_three']['de']->type, LOCALE_TRANSLATION_CURRENT, 'Translation of contrib_module_three found');
 
     // Check the new translation status.
     // The static cache needs to be flushed first to get the most recent data
@@ -462,7 +462,7 @@ function testUpdateImportSourceRemote() {
   }
 
   /**
-   * Test translation import from local sources.
+   * Tests translation import from local sources.
    *
    * Test conditions:
    *  - Source: local files only
@@ -490,12 +490,12 @@ function testUpdateImportSourceLocal() {
 
     // Check if the translation has been updated, using the status cache.
     $status = state()->get('locale.translation_status');
-    $this->assertEqual($status['contrib_module_one']['de']->type, 'current', 'Translation of contrib_module_one found');
-    $this->assertEqual($status['contrib_module_two']['de']->type, 'current', 'Translation of contrib_module_two found');
-    $this->assertEqual($status['contrib_module_three']['de']->type, 'current', 'Translation of contrib_module_three found');
+    $this->assertEqual($status['contrib_module_one']['de']->type, LOCALE_TRANSLATION_CURRENT, 'Translation of contrib_module_one found');
+    $this->assertEqual($status['contrib_module_two']['de']->type, LOCALE_TRANSLATION_CURRENT, 'Translation of contrib_module_two found');
+    $this->assertEqual($status['contrib_module_three']['de']->type, LOCALE_TRANSLATION_CURRENT, 'Translation of contrib_module_three found');
 
     // Check the new translation status.
-    // The static cache needs to be flushed firt to get the most recent data
+    // The static cache needs to be flushed first to get the most recent data
     // from the database. The function was called earlier during this test.
     drupal_static_reset('locale_translation_get_file_history');
     $history = locale_translation_get_file_history();
@@ -517,7 +517,7 @@ function testUpdateImportSourceLocal() {
   }
 
   /**
-   * Test translation import without a translations directory.
+   * Tests translation import without a translations directory.
    *
    * Test conditions:
    *  - Source: remote and local files
@@ -546,12 +546,12 @@ function testUpdateImportWithoutDirectory() {
 
     // Check if the translation has been updated, using the status cache.
     $status = state()->get('locale.translation_status');
-    $this->assertEqual($status['contrib_module_one']['de']->type, 'current', 'Translation of contrib_module_one found');
-    $this->assertEqual($status['contrib_module_two']['de']->type, 'current', 'Translation of contrib_module_two found');
-    $this->assertEqual($status['contrib_module_three']['de']->type, 'current', 'Translation of contrib_module_three found');
+    $this->assertEqual($status['contrib_module_one']['de']->type, LOCALE_TRANSLATION_CURRENT, 'Translation of contrib_module_one found');
+    $this->assertEqual($status['contrib_module_two']['de']->type, LOCALE_TRANSLATION_CURRENT, 'Translation of contrib_module_two found');
+    $this->assertEqual($status['contrib_module_three']['de']->type, LOCALE_TRANSLATION_CURRENT, 'Translation of contrib_module_three found');
 
     // Check the new translation status.
-    // The static cache needs to be flushed firt to get the most recent data
+    // The static cache needs to be flushed first to get the most recent data
     // from the database. The function was called earlier during this test.
     drupal_static_reset('locale_translation_get_file_history');
     $history = locale_translation_get_file_history();
@@ -572,7 +572,7 @@ function testUpdateImportWithoutDirectory() {
   }
 
   /**
-   * Test translation import with a translations directory and only overwrite
+   * Tests translation import with a translations directory and only overwrite
    * non-customized translations.
    *
    * Test conditions:
@@ -610,7 +610,7 @@ function testUpdateImportModeNonCustomized() {
   }
 
   /**
-   * Test translation import with a translations directory and don't overwrite
+   * Tests translation import with a translations directory and don't overwrite
    * any translation.
    *
    * Test conditions:
@@ -648,10 +648,13 @@ function testUpdateImportModeNone() {
   }
 
   /**
-   * Test automatic translation import when a module is enabled.
+   * Tests automatic translation import when a module is enabled.
    */
   function testEnableDisableModule() {
-    // Check is there is no translation yet.
+    // Make the hidden test modules look like a normal custom module.
+    state()->set('locale.test_system_info_alter', TRUE);
+
+    // Check if there is no translation yet.
     $this->assertTranslation('Tuesday', '', 'de');
 
     // Enable a module.
@@ -661,7 +664,7 @@ function testEnableDisableModule() {
     $this->drupalPost('admin/modules', $edit, t('Save configuration'));
 
     // Check if translations have been imported.
-    $this->assertRaw(t('One translation file imported. %number translations were added, %update translations were updated and %delete translations were removed.',
+    $this->assertText(t('One translation file imported. %number translations were added, %update translations were updated and %delete translations were removed.',
       array('%number' => 7, '%update' => 0, '%delete' => 0)), 'One translation file imported.');
     $this->assertTranslation('Tuesday', 'Dienstag', 'de');
 
@@ -684,31 +687,34 @@ function testEnableDisableModule() {
   }
 
   /**
-   * Test automatic translation import when a langauge is enabled.
+   * Tests automatic translation import when a langauge is enabled.
    *
    * When a language is added, the system will check for translations files of
    * enabled modules and will import them. When a language is removed the system
-   * will remove all translations of that langague from the database.
+   * will remove all translations of that langugue from the database.
    */
   function testEnableDisableLanguage() {
+    // Make the hidden test modules look like a normal custom module.
+    state()->set('locale.test_system_info_alter', TRUE);
+
     // Enable a module.
     $edit = array(
       'modules[Testing][locale_test_translate][enable]' => 'locale_test_translate',
     );
     $this->drupalPost('admin/modules', $edit, t('Save configuration'));
 
-    // Check is there is no Dutch translation yet.
+    // Check if there is no Dutch translation yet.
     $this->assertTranslation('Extraday', '', 'nl');
     $this->assertTranslation('Tuesday', 'Dienstag', 'de');
 
-    // Add a language
+    // Add a language.
     $edit = array(
       'predefined_langcode' => 'nl',
     );
     $this->drupalPost('admin/config/regional/language/add', $edit, t('Add language'));
 
     // Check if the right number of translations are added.
-    $this->assertRaw(t('One translation file imported. %number translations were added, %update translations were updated and %delete translations were removed.',
+    $this->assertText(t('One translation file imported. %number translations were added, %update translations were updated and %delete translations were removed.',
       array('%number' => 8, '%update' => 0, '%delete' => 0)), 'One language added.');
     $this->assertTranslation('Extraday', 'extra dag', 'nl');
 
@@ -716,34 +722,35 @@ function testEnableDisableLanguage() {
     $result = db_query("SELECT project FROM {locale_file} WHERE langcode='nl'")->fetchField();
     $this->assertTrue((boolean) $result, 'Files removed from file history');
 
-    // Remove a language
+    // Remove a language.
     $this->drupalPost('admin/config/regional/language/delete/nl', array(), t('Delete'));
 
     // Check if the language data is removed from the database.
     $result = db_query("SELECT project FROM {locale_file} WHERE langcode='nl'")->fetchField();
     $this->assertFalse($result, 'Files removed from file history');
 
-    // Check is there is no more Duth translation.
+    // Check that the Dutch translation is gone.
     $this->assertTranslation('Extraday', '', 'nl');
     $this->assertTranslation('Tuesday', 'Dienstag', 'de');
   }
 
-}
+  /**
+   * Tests automatic translation import when a custom langauge is enabled.
+   */
+  function testEnableCustomLanguage() {
+    // Make the hidden test modules look like a normal custom module.
+    state()->set('locale.test_system_info_alter', TRUE);
 
-/*
-   function testAutomaticModuleTranslationImportLanguageEnable() {
     // Enable a module.
     $edit = array(
       'modules[Testing][locale_test_translate][enable]' => 'locale_test_translate',
     );
     $this->drupalPost('admin/modules', $edit, t('Save configuration'));
 
-    // Code for the language - manually set to match the test translation file.
+    // Create and enable a custom language with language code 'xx' and a random
+    // name.
     $langcode = 'xx';
-    // The English name for the language.
     $name = $this->randomName(16);
-
-    // Create a custom language.
     $edit = array(
       'predefined_langcode' => 'custom',
       'langcode' => $langcode,
@@ -752,12 +759,12 @@ function testAutomaticModuleTranslationImportLanguageEnable() {
     );
     $this->drupalPost('admin/config/regional/language/add', $edit, t('Add custom language'));
 
-    // Ensure the translation file was automatically imported when language was
-    // added.
+    // Ensure the translation file is automatically imported when the language
+    // was added.
     $this->assertText(t('One translation file imported.'), t('Language file automatically imported.'));
-    $this->assertText(t('A translation string was skipped because of disallowed or malformed HTML'), t('Language file automatically imported.'));
+    $this->assertText(t('One translation string was skipped because of disallowed or malformed HTML'), t('Language file automatically imported.'));
 
-    // Ensure strings were successfully imported.
+    // Ensure the strings were successfully imported.
     $search = array(
       'string' => 'lundi',
       'langcode' => $langcode,
@@ -766,7 +773,7 @@ function testAutomaticModuleTranslationImportLanguageEnable() {
     $this->drupalPost('admin/config/regional/translate/translate', $search, t('Filter'));
     $this->assertNoText(t('No strings available.'), t('String successfully imported.'));
 
-    // Ensure multiline string was imported.
+    // Ensure the multiline string was imported.
     $search = array(
       'string' => 'Source string for multiline translation',
       'langcode' => $langcode,
@@ -787,4 +794,4 @@ function testAutomaticModuleTranslationImportLanguageEnable() {
     $this->assertText('Allowed HTML source string', t('String successfully imported.'));
     $this->assertNoText('Another allowed HTML source string', t('String with disallowed translation not imported.'));
   }
-*/
\ No newline at end of file
+}
diff --git a/core/modules/locale/locale.batch.inc b/core/modules/locale/locale.batch.inc
index 7bb35ef..e086869 100644
--- a/core/modules/locale/locale.batch.inc
+++ b/core/modules/locale/locale.batch.inc
@@ -8,6 +8,8 @@
 /**
  * Load the common translation API.
  */
+// @todo Combine functions differently in files to avoid unnecessary includes.
+// Follow-up issue http://drupal.org/node/1834298
 require_once DRUPAL_ROOT . '/core/modules/locale/locale.translation.inc';
 
 /**
@@ -29,8 +31,8 @@
 function locale_translation_batch_status_fetch_remote($source, &$context) {
   // Check the translation file at the remote server and update the source
   // data with the remote status.
-  if (isset($source->files['remote'])) {
-    $remote_file = $source->files['remote'];
+  if (isset($source->files[LOCALE_TRANSLATION_REMOTE])) {
+    $remote_file = $source->files[LOCALE_TRANSLATION_REMOTE];
     $result = locale_translation_http_check($remote_file->uri);
 
     if ($result) {
@@ -40,7 +42,7 @@ function locale_translation_batch_status_fetch_remote($source, &$context) {
       if (isset($result->updated)) {
         $remote_file->uri = isset($result->redirect_uri) ? $result->redirect_uri : $remote_file->uri;
         $remote_file->timestamp = $result->updated;
-        $source->files['remote'] = $remote_file;
+        $source->files[LOCALE_TRANSLATION_REMOTE] = $remote_file;
       }
       // Record success.
       $context['results']['files'][$source->name] = $source->name;
@@ -74,13 +76,13 @@ function locale_translation_batch_status_fetch_local($sources, &$context) {
   // Get the status of local translation files and store the result data in the
   // batch results for later processing.
   foreach ($sources as $source) {
-    if (isset($source->files['local'])) {
+    if (isset($source->files[LOCALE_TRANSLATION_LOCAL])) {
       locale_translation_source_check_file($source);
 
       // If remote data was collected before, we merge it into the newly
       // collected result.
       if (isset($context['results']['sources'][$source->name][$source->langcode])) {
-        $source->files['remote'] = $context['results']['sources'][$source->name][$source->langcode]->files['remote'];
+        $source->files[LOCALE_TRANSLATION_REMOTE] = $context['results']['sources'][$source->name][$source->langcode]->files[LOCALE_TRANSLATION_REMOTE];
       }
 
       // Record success and store the updated source data.
@@ -113,26 +115,26 @@ function locale_translation_batch_status_compare(&$context) {
   if (isset($context['results']['sources'])) {
     foreach ($context['results']['sources'] as $project => $langcodes) {
       foreach ($langcodes as $langcode => $source) {
-        $local = isset($source->files['local']) ? $source->files['local'] : NULL;
-        $remote = isset($source->files['remote']) ? $source->files['remote'] : NULL;
+        $local = isset($source->files[LOCALE_TRANSLATION_LOCAL]) ? $source->files[LOCALE_TRANSLATION_LOCAL] : NULL;
+        $remote = isset($source->files[LOCALE_TRANSLATION_REMOTE]) ? $source->files[LOCALE_TRANSLATION_REMOTE] : NULL;
 
-        // The available translation files are compare and data of the most recent
-        // file is used to update the source object.
+        // The available translation files are compared and data of the most
+        // recent file is used to update the source object.
         $file = _locale_translation_source_compare($local, $remote) == LOCALE_TRANSLATION_SOURCE_COMPARE_LT ? $remote : $local;
         if (isset($file->timestamp)) {
           $source->type = $file->type;
           $source->timestamp = $file->timestamp;
         }
 
-        // Compare the available translation with the current translations status.
-        // If the project/language was translated before and it is more recent
-        // than the most recent translation, the translation is up to date. Which
-        // is marked in the source object with type "current".
+        // Compare the available translation with the current translations
+        // status. If the project/language was translated before and it is more
+        // recent than the most recent translation, the translation is up to
+        // date. Which is marked in the source object with type "current".
         if (isset($history[$source->project][$source->langcode])) {
           $current = $history[$source->project][$source->langcode];
           // Add the current translation to the source object to save it in
           // the status cache.
-          $source->files['current'] = $current;
+          $source->files[LOCALE_TRANSLATION_CURRENT] = $current;
 
           if (isset($source->type)) {
             $available = $source->files[$source->type];
@@ -191,7 +193,7 @@ function locale_translation_batch_status_finished($success, $results) {
 }
 
 /**
- * Load translation source data for the projects to be updated.
+ * Loads translation source data for the projects to be updated.
  *
  * Source data is loaded from cache and stored in the context results array.
  * Source data contains the translations status per project / per language
@@ -200,10 +202,10 @@ function locale_translation_batch_status_finished($success, $results) {
  * so that other batch operations can take this data as input for their
  * operation.
  *
- * @see locale_translation_batch_fetch_download().
- * @see locale_translation_batch_fetch_import().
- * @see locale_translation_batch_fetch_update_status().
- * @see locale_translation_batch_status_compare().
+ * @see locale_translation_batch_fetch_download()
+ * @see locale_translation_batch_fetch_import()
+ * @see locale_translation_batch_fetch_update_status()
+ * @see locale_translation_batch_status_compare()
  */
 function locale_translation_batch_fetch_sources($projects, $langcodes, &$context) {
   $context['results']['input'] = locale_translation_load_sources($projects, $langcodes);
@@ -230,23 +232,23 @@ function locale_translation_batch_fetch_sources($projects, $langcodes, &$context
  * @param $context
  *   Batch context array.
  *
- * @see locale_translation_batch_fetch_sources().
- * @see locale_translation_batch_fetch_import().
- * @see locale_translation_batch_fetch_update_status().
- * @see locale_translation_batch_status_compare().
+ * @see locale_translation_batch_fetch_sources()
+ * @see locale_translation_batch_fetch_import()
+ * @see locale_translation_batch_fetch_update_status()
+ * @see locale_translation_batch_status_compare()
  */
 function locale_translation_batch_fetch_download($project, $langcode, &$context) {
   $sources = $context['results']['input'];
   if (isset($sources[$project . ':' . $langcode])) {
     $source = $sources[$project . ':' . $langcode];
-    if (isset($source->type) && $source->type == 'remote') {
+    if (isset($source->type) && $source->type == LOCALE_TRANSLATION_REMOTE) {
       $t = get_t();
-      if ($file = locale_translation_download_source($source->files['remote'])) {
+      if ($file = locale_translation_download_source($source->files[LOCALE_TRANSLATION_REMOTE])) {
         $context['message'] = $t('Importing: %name.', array('%name' => $file->filename));
-        $source->files['download'] = $file;
+        $source->files[LOCALE_TRANSLATION_DOWNLOADED] = $file;
       }
       else {
-        $context['results']['failed_files'][] = $source->files['remote'];
+        $context['results']['failed_files'][] = $source->files[LOCALE_TRANSLATION_REMOTE];
       }
       $context['results']['sources'][$project][$langcode] = $source;
     }
@@ -256,7 +258,7 @@ function locale_translation_batch_fetch_download($project, $langcode, &$context)
 /**
  * Batch process: Import translation file.
  *
- * This batch operations imports either a local gettext file or a downloaded
+ * This batch operation imports either a local gettext file or a downloaded
  * remote gettext file. In case of a downloaded file the location of the
  * temporary file is found in the $context['results']['sources']. The temporary
  * file will be deleted after importing or will be moved to the local
@@ -272,30 +274,30 @@ function locale_translation_batch_fetch_download($project, $langcode, &$context)
  * @param $context
  *   Batch context array.
  *
- * @see locale_translate_batch_import_files().
- * @see locale_translation_batch_fetch_sources().
- * @see locale_translation_batch_fetch_download().
- * @see locale_translation_batch_fetch_update_status().
- * @see locale_translation_batch_status_compare().
+ * @see locale_translate_batch_import_files()
+ * @see locale_translation_batch_fetch_sources()
+ * @see locale_translation_batch_fetch_download()
+ * @see locale_translation_batch_fetch_update_status()
+ * @see locale_translation_batch_status_compare()
  */
 function locale_translation_batch_fetch_import($project, $langcode, $options, &$context) {
   $sources = $context['results']['input'];
   if (isset($sources[$project . ':' . $langcode])) {
     $source = $sources[$project . ':' . $langcode];
     if (isset($source->type)) {
-      if ($source->type == 'remote' || $source->type == 'local') {
+      if ($source->type == LOCALE_TRANSLATION_REMOTE || $source->type == LOCALE_TRANSLATION_LOCAL) {
 
         $t = get_t();
-        // If we are working on a remote file we will import the downloaded file and
-        // use the result data from the
-        if ($source->type == 'remote') {
-          if (isset($context['results']['sources'][$source->project][$source->langcode]->files['download'])) {
-            $import_type = 'download';
+        // If we are working on a remote file we will import the downloaded
+        // file. If the file was local just mark the result as such.
+        if ($source->type == LOCALE_TRANSLATION_REMOTE) {
+          if (isset($context['results']['sources'][$source->project][$source->langcode]->files[LOCALE_TRANSLATION_DOWNLOADED])) {
+            $import_type = LOCALE_TRANSLATION_DOWNLOADED;
             $source_result = $context['results']['sources'][$source->project][$source->langcode];
           }
         }
         else {
-          $import_type = 'local';
+          $import_type = LOCALE_TRANSLATION_LOCAL;
           $source_result = $source;
         }
 
@@ -314,43 +316,43 @@ function locale_translation_batch_fetch_import($project, $langcode, $options, &$
           if (isset($context['results']['files'][$file->uri])) {
             $context['message'] = $t('Imported: %name.', array('%name' => $file->filename));
 
-            // Keep the data of imported source. In following batch operations
-            // it will be saved in the {locale_file} table.
-            $source_result->files['import'] = $source_result->files[$source->type];
-
-            // Downloaded files are stored in the temporary files directory. On
-            // succesfull import, the files are moved to the local destination
-            // directory if files should be kept locally. Otherwise the
-            // temporary files are deleted.
-            if ($import_type == 'download' && variable_get('locale_translate_file_directory', conf_path() . '/files/translations') && isset($source_result->files['local'])) {
-              // Move the temporary file to the local translations directory.
-              if (file_unmanaged_move($file->uri, $source_result->files['local']->uri, FILE_EXISTS_REPLACE)) {
+            // Keep the data of imported source. In the following batch
+            // operation it will be saved in the {locale_file} table.
+            $source_result->files[LOCALE_TRANSLATION_IMPORTED] = $source_result->files[$source->type];
+
+            // Downloaded files are stored in the temporary files directory. If
+            // files should be kept locally, they will be moved to the local
+            // translations after successfull import. Otherwise the temporary
+            // file is are deleted after being imported.
+            if ($import_type == LOCALE_TRANSLATION_DOWNLOADED && variable_get('locale_translate_file_directory', conf_path() . '/files/translations') && isset($source_result->files[LOCALE_TRANSLATION_LOCAL])) {
+              if (file_unmanaged_move($file->uri, $source_result->files[LOCALE_TRANSLATION_LOCAL]->uri, FILE_EXISTS_REPLACE)) {
                 // The downloaded file is now moved to the local file location.
                 // From this point forward we can treat it as if we imported a
                 // local file.
-                $import_type = 'local';
+                $import_type = LOCALE_TRANSLATION_LOCAL;
               }
             }
-            if ($import_type == 'download') {
-              // The temporary file is now imported and will not be used further.
-              // Store the timestamp and delete the file.
+            // The downloaded file is imported but will not be stored locally.
+            // Store the timestamp and delete the file.
+            if ($import_type == LOCALE_TRANSLATION_DOWNLOADED) {
               $timestamp = filemtime($source_result->files[$import_type]->uri);
-              $source_result->files['import']->timestamp = $timestamp;
-              $source_result->files['import']->last_checked = REQUEST_TIME;
+              $source_result->files[LOCALE_TRANSLATION_IMPORTED]->timestamp = $timestamp;
+              $source_result->files[LOCALE_TRANSLATION_IMPORTED]->last_checked = REQUEST_TIME;
               file_unmanaged_delete($file->uri);
             }
-            if ($import_type == 'local') {
-              // Import type is 'local'.
+            // If the translation file is stored in the local directory. The
+            // timestamp of the file is stored.
+            if ($import_type == LOCALE_TRANSLATION_LOCAL) {
               $timestamp = filemtime($source_result->files[$import_type]->uri);
-              $source_result->files['local']->timestamp = $timestamp;
-              $source_result->files['import']->timestamp = $timestamp;
-              $source_result->files['import']->last_checked = REQUEST_TIME;
+              $source_result->files[LOCALE_TRANSLATION_LOCAL]->timestamp = $timestamp;
+              $source_result->files[LOCALE_TRANSLATION_IMPORTED]->timestamp = $timestamp;
+              $source_result->files[LOCALE_TRANSLATION_IMPORTED]->last_checked = REQUEST_TIME;
 
             }
           }
           else {
             // File import failed. We can delete the temporary file.
-            if ($import_type == 'download') {
+            if ($import_type == LOCALE_TRANSLATION_DOWNLOADED) {
               file_unmanaged_delete($file->uri);
             }
           }
@@ -370,10 +372,10 @@ function locale_translation_batch_fetch_import($project, $langcode, $options, &$
  * @param $context
  *   Batch context array.
  *
- * @see locale_translation_batch_fetch_sources().
- * @see locale_translation_batch_fetch_download().
- * @see locale_translation_batch_fetch_import().
- * @see locale_translation_batch_status_compare().
+ * @see locale_translation_batch_fetch_sources()
+ * @see locale_translation_batch_fetch_download()
+ * @see locale_translation_batch_fetch_import()
+ * @see locale_translation_batch_status_compare()
  */
 function locale_translation_batch_fetch_update_status(&$context) {
   $results = array();
@@ -383,20 +385,20 @@ function locale_translation_batch_fetch_update_status(&$context) {
       foreach ($langcodes as $langcode => $source) {
 
         // Store the state of the imported translations in {locale_file} table.
-        // During the batch execution data of imported files is temporary stored
-        // in $context['results']['sources']. Now is will be stored in the
-        // database. Afterwards the temporary import and download data can be
-        // deleted.
-        if (isset($source->files['import'])) {
-          $file = $source->files['import'];
+        // During the batch execution the data of the imported files is
+        // temporary stored in $context['results']['sources']. Now it will be
+        // stored in the database. Afterwards the temporary import and download
+        // data can be deleted.
+        if (isset($source->files[LOCALE_TRANSLATION_IMPORTED])) {
+          $file = $source->files[LOCALE_TRANSLATION_IMPORTED];
           locale_translation_update_file_history($file);
-          unset($source->files['import']);
+          unset($source->files[LOCALE_TRANSLATION_IMPORTED]);
         }
-        unset($source->files['download']);
+        unset($source->files[LOCALE_TRANSLATION_DOWNLOADED]);
 
         // The source data is now up to date. Data of local and/or remote source
         // file is up to date including an updated time stamp. In a next batch
-        // operation this can be use to update the translation status.
+        // operation this can be used to update the translation status.
         $context['results']['sources'][$project][$langcode] = $source;
       }
     }
@@ -406,9 +408,9 @@ function locale_translation_batch_fetch_update_status(&$context) {
 /**
  * Batch finished callback: Set result message.
  *
- * @param $success
+ * @param boolean $success
  *   TRUE if batch succesfully completed.
- * @param $results
+ * @param array
  *   Batch results.
  */
 function locale_translation_batch_fetch_finished($success, $results) {
@@ -459,7 +461,7 @@ function locale_translation_http_check($uri, $headers = array()) {
 }
 
 /**
- * Download source file from a remote server.
+ * Downloads source file from a remote server.
  *
  * The downloaded file is stored in the temporary files directory.
  *
@@ -480,11 +482,11 @@ function locale_translation_download_source($source_file) {
     $file->project = $source_file->project;
     $file->langcode = $source_file->langcode;
     $file->version = $source_file->version;
-    $file->type = 'download';
+    $file->type = LOCALE_TRANSLATION_DOWNLOADED;
     $file->uri = $uri;
     $file->filename = $source_file->filename;
     return $file;
   }
-  watchdog('locale', 'Unable to download translation file @uri.', array('@uri' => $source->files['remote']->uri), WATCHDOG_ERROR);
+  watchdog('locale', 'Unable to download translation file @uri.', array('@uri' => $source->files[LOCALE_TRANSLATION_REMOTE]->uri), WATCHDOG_ERROR);
   return FALSE;
 }
diff --git a/core/modules/locale/locale.bulk.inc b/core/modules/locale/locale.bulk.inc
index 586d626..46c5453 100644
--- a/core/modules/locale/locale.bulk.inc
+++ b/core/modules/locale/locale.bulk.inc
@@ -428,8 +428,8 @@ function locale_translate_batch_import($file, $options, &$context) {
       }
 
       // Add the reported values to the statistics for this file.
-      // Each import itteration reports statistics in an array. The results of
-      // each itteration are added and merged here and stored per file.
+      // Each import iteration reports statistics in an array. The results of
+      // each iteration are added and merged here and stored per file.
       if (!isset($context['results']['stats']) || !isset($context['results']['stats'][$file->uri])) {
         $context['results']['stats'][$file->uri] = array();
       }
@@ -463,10 +463,11 @@ function locale_translate_batch_import($file, $options, &$context) {
 function locale_translate_batch_import_save($context) {
   if (isset($context['results']['files'])) {
     foreach ($context['results']['files'] as $file) {
-      // Update the file history if both project and version are known. This table
-      // is used by the automated translation update function which tracks
-      // translation status of module and themes in the system. Other data
-      // than installed projects would stay in the table for ever never.
+      // Update the file history if both project and version are known. This
+      // table is used by the automated translation update function which tracks
+      // translation status of module and themes in the system. Other
+      // translation files are not tracked and are therefore not stored in this
+      // table.
       if ($file->project && $file->version) {
         $file->last_checked = REQUEST_TIME;
         locale_translation_update_file_history($file);
@@ -613,7 +614,6 @@ function locale_translate_file_attach_properties($file, $options = array()) {
  *   TRUE if files are removed sucessfully. FALSE if one or more files could
  *   not be deleted.
  */
-// @todo Move this function to translation.inc?
 function locale_translate_delete_translation_files($projects = array(), $langcodes = array()) {
   $fail = FALSE;
   locale_translation_file_history_delete($projects, $langcodes);
diff --git a/core/modules/locale/locale.compare.inc b/core/modules/locale/locale.compare.inc
index 333ee53..86d6acf 100644
--- a/core/modules/locale/locale.compare.inc
+++ b/core/modules/locale/locale.compare.inc
@@ -10,6 +10,8 @@
 /**
  * Load the common translation API.
  */
+// @todo Combine functions differently in files to avoid unnecessary includes.
+// Follow-up issue http://drupal.org/node/1834298
 require_once DRUPAL_ROOT . '/core/modules/locale/locale.translation.inc';
 
 /**
@@ -273,7 +275,7 @@ function locale_translation_check_projects_batch($projects = array(), $langcodes
 }
 
 /**
- * Build a batch to get the status of remote and local translation files.
+ * Builds a batch to get the status of remote and local translation files.
  *
  * The batch process fetches the state of both remote and (if configured) local
  * translation files. The data of the most recent translation is stored per
@@ -307,7 +309,8 @@ function locale_translation_batch_status_build($projects = array(), $langcodes =
 }
 
 /**
- * Helper function to construct batch operations checking remote translation status.
+ * Helper function to construct batch operations checking remote translation
+ * status.
  *
  * @param array projects
  *   Array of project names to be processed.
@@ -378,7 +381,7 @@ function locale_translation_check_projects_local($projects = array(), $langcodes
         $current = $history[$source->project][$source->langcode];
         // Add the current translation to the source object to save it in
         // the status cache.
-        $source->files['current'] = $current;
+        $source->files[LOCALE_TRANSLATION_CURRENT] = $current;
 
         if (isset($source->type)) {
           $available = $source->files[$source->type];
diff --git a/core/modules/locale/locale.fetch.inc b/core/modules/locale/locale.fetch.inc
index e5278e7..b65aa4b 100755
--- a/core/modules/locale/locale.fetch.inc
+++ b/core/modules/locale/locale.fetch.inc
@@ -8,10 +8,12 @@
 /**
  * Load the common translation API.
  */
+// @todo Combine functions differently in files to avoid unnecessary includes.
+// Follow-up issue http://drupal.org/node/1834298
 require_once DRUPAL_ROOT . '/core/modules/locale/locale.translation.inc';
 
 /**
- * Build a batch to check, download and import project translations.
+ * Builds a batch to check, download and import project translations.
  *
  * @param array $projects
  *   Array of project names for which to update the translations. Defaults to
@@ -25,7 +27,6 @@
  *   Batch definition array.
  */
 function locale_translation_batch_update_build($projects = array(), $langcodes = array(), $options = array()) {
-  // @todo Merge compare.inc and fetch.inc? Merge with batch.inc?
   module_load_include('compare.inc', 'locale');
   $t = get_t();
   $projects = $projects ? $projects : array_keys(locale_translation_get_projects());
@@ -46,7 +47,7 @@ function locale_translation_batch_update_build($projects = array(), $langcodes =
 }
 
 /**
- * Build a batch to download and import project translations.
+ * Builds a batch to download and import project translations.
  *
  * @param array $projects
  *   Array of project names for which to check the state of translation files.
diff --git a/core/modules/locale/locale.install b/core/modules/locale/locale.install
index fde8d6a..3b26178 100644
--- a/core/modules/locale/locale.install
+++ b/core/modules/locale/locale.install
@@ -708,7 +708,6 @@ function locale_update_8010() {
         'default' => '',
       ),
       'uri' => array(
-        'description' => 'File system path for importing the file.',
         'type' => 'varchar',
         'length' => 255,
         'not null' => TRUE,
@@ -850,11 +849,9 @@ function locale_update_8015() {
         'description' => 'Version tag of the imported file.',
       ),
       'uri' => array(
-        'type' => 'varchar',
-        'length' => 255,
+        'description' => 'File system path for importing the file.',
+        'type' => 'text',
         'not null' => TRUE,
-        'default' => '',
-        'description' => 'URI of the remote file, the resulting local file or the locally imported file.',
       ),
       'timestamp' => array(
         'type' => 'int',
diff --git a/core/modules/locale/locale.module b/core/modules/locale/locale.module
index db230ff..8b7235c 100644
--- a/core/modules/locale/locale.module
+++ b/core/modules/locale/locale.module
@@ -115,6 +115,30 @@
  */
 const LOCALE_TRANSLATION_OVERWRITE_NONE = 'none';
 
+/**
+ * Translation source is a remote file.
+ */
+const LOCALE_TRANSLATION_REMOTE = 'remote';
+
+/**
+ * Translation source is a local file.
+ */
+const LOCALE_TRANSLATION_LOCAL = 'local';
+
+/**
+ * Translation source is the current translation.
+ */
+const LOCALE_TRANSLATION_CURRENT = 'current';
+
+/**
+ * Translation source is a downloaded file.
+ */
+const LOCALE_TRANSLATION_DOWNLOADED = 'download';
+
+/**
+ * Translation source is an imported file.
+ */
+const LOCALE_TRANSLATION_IMPORTED = 'import';
 
 /**
  * Implements hook_help().
@@ -824,7 +848,7 @@ function locale_preprocess_node(&$variables) {
 }
 
 /**
- * Get current translation status from the {locale_file} table.
+ * Gets current translation status from the {locale_file} table.
  *
  * @return array
  *   Array of translation file objects.
@@ -836,7 +860,7 @@ function locale_translation_get_file_history() {
     // Get file history from the database.
     $result = db_query('SELECT project, langcode, filename, version, uri, timestamp, last_checked FROM {locale_file}');
     foreach ($result as $file) {
-      $file->type = 'current';
+      $file->type = LOCALE_TRANSLATION_CURRENT;
       $history[$file->project][$file->langcode] = $file;
     }
   }
@@ -844,9 +868,9 @@ function locale_translation_get_file_history() {
 }
 
 /**
- * Update the {locale_file} table.
+ * Updates the {locale_file} table.
  *
- * @param $file
+ * @param object $file
  *   Object representing the file just imported.
  *
  * @return integer
@@ -866,7 +890,7 @@ function locale_translation_update_file_history($file) {
 }
 
 /**
- * Delete the history of downloaded translations.
+ * Deletes the history of downloaded translations.
  *
  * @param array $projects
  *   Project name(s) to be deleted from the file history. If both project(s) and
@@ -886,7 +910,7 @@ function locale_translation_file_history_delete($projects = array(), $langcodes
 }
 
 /**
- * Save the status of translation sources in static cache.
+ * Saves the status of translation sources in static cache.
  *
  * @param array $data
  *   Array of translation source data, structured by project name and langcode.
diff --git a/core/modules/locale/locale.pages.inc b/core/modules/locale/locale.pages.inc
index f0c05e6..ad9f1f6 100644
--- a/core/modules/locale/locale.pages.inc
+++ b/core/modules/locale/locale.pages.inc
@@ -562,20 +562,25 @@ function locale_translate_settings_submit($form, &$form_state) {
 
   switch ($values['overwrite']) {
     case LOCALE_TRANSLATION_OVERWRITE_ALL:
-      $config->set('translation.overwrite_customized', TRUE)->save();
-      $config->set('translation.overwrite_not_customized', TRUE)->save();
+      $config
+        ->set('translation.overwrite_customized', TRUE)
+        ->set('translation.overwrite_not_customized', TRUE);
       break;
     case LOCALE_TRANSLATION_OVERWRITE_NON_CUSTOMIZED:
-      $config->set('translation.overwrite_customized', FALSE)->save();
-      $config->set('translation.overwrite_not_customized', TRUE)->save();
+      $config
+        ->set('translation.overwrite_customized', FALSE)
+        ->set('translation.overwrite_not_customized', TRUE);
       break;
     case LOCALE_TRANSLATION_OVERWRITE_NONE:
-      $config->set('translation.overwrite_customized', FALSE)->save();
-      $config->set('translation.overwrite_not_customized', FALSE)->save();
+      $config
+        ->set('translation.overwrite_customized', FALSE)
+        ->set('translation.overwrite_not_customized', FALSE);
       break;
   }
 
-  $config->set('translation.check_disabled_modules', $values['check_disabled_modules'])->save();
+  $config
+    ->set('translation.check_disabled_modules', $values['check_disabled_modules'])
+    ->save();
 
   // Invalidate the cached translation status when the configuration setting of
   // 'use_source' and 'check_disabled_modules' change.
@@ -592,7 +597,6 @@ function locale_translate_settings_submit($form, &$form_state) {
  */
 function locale_translation_status_form($form, &$form_state) {
   module_load_include('compare.inc', 'locale');
-  //locale_translation_flush_projects();
 
   $languages = locale_translatable_language_list();
   $status = state()->get('locale.translation_status');
@@ -603,7 +607,7 @@ function locale_translation_status_form($form, &$form_state) {
 
   // @todo Add user interface update for translation update.
   // Followup issues: Display translation status http://drupal.org/node/1804702
-  // and Translations update feature user experience http://drupal.org/node/1029554
+  // and Translations update feature UX http://drupal.org/node/1029554
   $form['langcodes'] = array(
     '#type' => 'value',
     '#value' => drupal_map_assoc(array_keys($languages)),
diff --git a/core/modules/locale/locale.translation.inc b/core/modules/locale/locale.translation.inc
index a250e4d..d6060f6 100644
--- a/core/modules/locale/locale.translation.inc
+++ b/core/modules/locale/locale.translation.inc
@@ -41,14 +41,13 @@
  * disabled this function will return the last known module state. The status
  * will only be updated once Update module is enabled.
  *
- * @see locale_translation_build_projects().
- *
  *  @params array $project_names
  *    Array of names of the projects to get.
  *
  * @return array
- *   Array of project data for translation update. See
- *   locale_translation_build_projects() for details.
+ *   Array of project data for translation update.
+ *
+ * @see locale_translation_build_projects()
  */
 function locale_translation_get_projects($project_names = array()) {
   $projects = &drupal_static(__FUNCTION__, array());
@@ -80,14 +79,14 @@ function locale_translation_get_projects($project_names = array()) {
 }
 
 /**
- * Clear the projects cache.
+ * Clears the projects cache.
  */
 function locale_translation_clear_cache_projects() {
   drupal_static('locale_translation_get_projects', array());
 }
 
 /**
- * Load cached translation sources containing current translation status.
+ * Loads cached translation sources containing current translation status.
  *
  * @param array $projects
  *   Array of project names. Defaults to all translatable projects.
@@ -97,7 +96,7 @@ function locale_translation_clear_cache_projects() {
  * @return array
  *   Array of source objects. Keyed with <project name>:<language code>.
  *
- * @see locale_translation_source_build().
+ * @see locale_translation_source_build()
  */
 function locale_translation_load_sources($projects = NULL, $langcodes = NULL) {
   $sources = array();
@@ -127,7 +126,7 @@ function locale_translation_load_sources($projects = NULL, $langcodes = NULL) {
  * @return array
  *   Array of source objects. Keyed with <project name>:<language code>.
  *
- * @see locale_translation_source_build().
+ * @see locale_translation_source_build()
  */
 function locale_translation_build_sources($projects = array(), $langcodes = array()) {
   $sources = array();
@@ -144,7 +143,7 @@ function locale_translation_build_sources($projects = array(), $langcodes = arra
 }
 
 /**
- * Check whether a po file exists in the local filesystem.
+ * Checks whether a po file exists in the local filesystem.
  *
  * It will search in the directory set in the translation source. Which defaults
  * to the "translations://" stream wrapper path. The directory may contain any
@@ -156,22 +155,23 @@ function locale_translation_build_sources($projects = array(), $langcodes = arra
  * using the server_pattern directive in the module's .info file or by using
  * hook_locale_translation_projects_alter().
  *
- * @param stdClass $source
+ * @param object $source
  *   Translation source object.
- *   @see locale_translation_source_build()
  *
  * @return stdClass
  *   File object (filename, basename, name) updated with data of the po file.
  *   On success the files property of the source object is updated.
- *   files['local']:
+ *   files[LOCALE_TRANSLATION_LOCAL]:
  *   - "uri": File name and path.
  *   - "timestamp": Last updated time of the po file.
  *   FALSE if the file is not found.
+ *
+ * @see locale_translation_source_build()
  */
 function locale_translation_source_check_file(&$source) {
-  if (isset($source->files['local'])) {
-    $directory = $source->files['local']->directory;
-    $filename = '/' . preg_quote($source->files['local']->filename) . '$/';
+  if (isset($source->files[LOCALE_TRANSLATION_LOCAL])) {
+    $directory = $source->files[LOCALE_TRANSLATION_LOCAL]->directory;
+    $filename = '/' . preg_quote($source->files[LOCALE_TRANSLATION_LOCAL]->filename) . '$/';
 
     // If the directory contains a stream wrapper, it is converted to a real
     // path. This is required for file_scan_directory() which can not handle
@@ -182,8 +182,8 @@ function locale_translation_source_check_file(&$source) {
 
     if ($files = file_scan_directory($directory, $filename, array('key' => 'name', 'recurse' => FALSE))) {
       $file = current($files);
-      $source->files['local']->uri = $file->uri;
-      $source->files['local']->timestamp = filemtime($file->uri);
+      $source->files[LOCALE_TRANSLATION_LOCAL]->uri = $file->uri;
+      $source->files[LOCALE_TRANSLATION_LOCAL]->timestamp = filemtime($file->uri);
       return $file;
     }
   }
@@ -191,14 +191,14 @@ function locale_translation_source_check_file(&$source) {
 }
 
 /**
- * Build abstract translation source.
+ * Builds abstract translation source.
  *
- * @param stdClass $project
+ * @param object $project
  *   Project object.
  * @param string $langcode
  *   Language code.
  * @param string $filename
- *   File name of translation file. May contains placeholders.
+ *   File name of translation file. May contain placeholders.
  *
  * @return object
  *   Source object:
@@ -211,12 +211,16 @@ function locale_translation_source_check_file(&$source) {
  *   - "files": Array of file objects containing properties of local and remote
  *     translation files.
  *   Other processes can add the following properties:
- *   - "type": Most recent file type 'remote' or 'local'. Corresponding with
- *     a key of the "files" array.
+ *   - "type": Most recent file type LOCALE_TRANSLATION_REMOTE or
+ *      LOCALE_TRANSLATION_LOCAL. Corresponding with a key of the
+ *      "files" array.
  *   - "timestamp": Timestamp of the most recent translation file.
- *   The "files" array can hold file objects of type: 'local', 'remote',
- *   'download', 'import' and 'current'. Each contains following properties:
- *   - "type": The object type ('local', 'remote', etc. see above).
+ *   The "files" array can hold file objects of type:
+ *   LOCALE_TRANSLATION_LOCAL, LOCALE_TRANSLATION_REMOTE,
+ *   LOCALE_TRANSLATION_DOWNLOADED, LOCALE_TRANSLATION_IMPORTED and
+ *   LOCALE_TRANSLATION_CURRENT. Each contains following properties:
+ *   - "type": The object type (LOCALE_TRANSLATION_LOCAL,
+ *     LOCALE_TRANSLATION_REMOTE, etc. see above).
  *   - "project": Project name.
  *   - "langcode": Language code.
  *   - "version": Project version.
@@ -239,41 +243,41 @@ function locale_translation_source_build($project, $langcode, $filename = NULL)
   $filename = $filename ? $filename : config('locale.settings')->get('translation.default_filename');
 
   // If the server_pattern contains a remote file path we will check for a
-  // remote file. The local version of this file will will only be checked is a
+  // remote file. The local version of this file will only be checked if a
   // translations directory has been defined. If the server_pattern is a local
   // file path we will only check for a file in the local file system.
   $files = array();
   if (_locale_translation_file_is_remote($source->server_pattern)) {
-    $files['remote'] = (object) array(
+    $files[LOCALE_TRANSLATION_REMOTE] = (object) array(
       'project' => $project->name,
       'langcode' => $langcode,
       'version' => $project->version,
-      'type' => 'remote',
+      'type' => LOCALE_TRANSLATION_REMOTE,
       'filename' => locale_translation_build_server_pattern($source, basename($source->server_pattern)),
       'uri' => locale_translation_build_server_pattern($source, $source->server_pattern),
     );
     if (variable_get('locale_translate_file_directory', conf_path() . '/files/translations')) {
-      $files['local'] = (object) array(
+      $files[LOCALE_TRANSLATION_LOCAL] = (object) array(
         'project' => $project->name,
         'langcode' => $langcode,
         'version' => $project->version,
-        'type' => 'local',
+        'type' => LOCALE_TRANSLATION_LOCAL,
         'filename' => locale_translation_build_server_pattern($source, $filename),
         'directory' => 'translations://',
       );
-      $files['local']->uri = $files['local']->directory . $files['local']->filename;
+      $files[LOCALE_TRANSLATION_LOCAL]->uri = $files[LOCALE_TRANSLATION_LOCAL]->directory . $files[LOCALE_TRANSLATION_LOCAL]->filename;
     }
   }
   else {
-    $files['local'] = (object) array(
+    $files[LOCALE_TRANSLATION_LOCAL] = (object) array(
       'project' => $project->name,
       'langcode' => $langcode,
       'version' => $project->version,
-      'type' => 'local',
+      'type' => LOCALE_TRANSLATION_LOCAL,
       'filename' => locale_translation_build_server_pattern($source, basename($source->server_pattern)),
       'directory' => locale_translation_build_server_pattern($source, drupal_dirname($source->server_pattern)),
     );
-    $files['local']->uri = $files['local']->directory . '/' . $files['local']->filename;
+    $files[LOCALE_TRANSLATION_LOCAL]->uri = $files[LOCALE_TRANSLATION_LOCAL]->directory . '/' . $files[LOCALE_TRANSLATION_LOCAL]->filename;
   }
   $source->files = $files;
 
@@ -303,9 +307,9 @@ function _locale_translation_file_is_remote($uri) {
  * The timestamp property of the source objects are used to determine which is
  * the newer one.
  *
- * @param stdClass $source1
+ * @param object $source1
  *   Source object of the first translation source.
- * @param stdClass $source2
+ * @param object $source2
  *   Source object of available update.
  *
  * @return integer
@@ -337,7 +341,7 @@ function _locale_translation_source_compare($source1, $source2) {
 }
 
 /**
- * Return default import options for translation update.
+ * Returns default import options for translation update.
  *
  * @return array
  *   Array of translation import options.
@@ -351,4 +355,4 @@ function _locale_translation_default_update_options() {
       'customized' => $config->get('translation.overwrite_customized'),
     ),
   );
-}
\ No newline at end of file
+}
diff --git a/core/modules/locale/tests/modules/locale_test/locale_test.module b/core/modules/locale/tests/modules/locale_test/locale_test.module
index a77472f..8f87ddc 100644
--- a/core/modules/locale/tests/modules/locale_test/locale_test.module
+++ b/core/modules/locale/tests/modules/locale_test/locale_test.module
@@ -17,7 +17,7 @@ function locale_test_system_info_alter(&$info, $file, $type) {
   // To test the module detection proces by locale_project_list() the
   // test modules should mimic a custom module. I.e. be non-hidden.
   if (state()->get('locale.test_system_info_alter')) {
-    if ($file->name == 'locale_test' || $file->name == 'locale_test_disabled') {
+    if ($file->name == 'locale_test' || $file->name == 'locale_test_translate') {
       // Don't hide the module.
       $info['hidden'] = FALSE;
     }
diff --git a/core/modules/locale/tests/modules/locale_test_disabled/locale_test_disabled.info b/core/modules/locale/tests/modules/locale_test_disabled/locale_test_disabled.info
deleted file mode 100644
index 7eddf25..0000000
--- a/core/modules/locale/tests/modules/locale_test_disabled/locale_test_disabled.info
+++ /dev/null
@@ -1,10 +0,0 @@
-name = Disabled locale test
-description = Disabled support module for locale module testing.
-package = Testing
-version = VERSION
-core = 8.x
-hidden = TRUE
-project = locale_test_disabled
-
-; Definitions for interface translation.
-interface translation project = locale_test_disabled
diff --git a/core/modules/locale/tests/modules/locale_test_disabled/locale_test_disabled.module b/core/modules/locale/tests/modules/locale_test_disabled/locale_test_disabled.module
deleted file mode 100644
index 0003e96..0000000
--- a/core/modules/locale/tests/modules/locale_test_disabled/locale_test_disabled.module
+++ /dev/null
@@ -1,6 +0,0 @@
-<?php
-
-/**
- * @file
- * Simulate a disabled contrib module for Locale test scripts.
- */
diff --git a/core/modules/locale/tests/modules/locale_test_translate/locale_test_translate.info b/core/modules/locale/tests/modules/locale_test_translate/locale_test_translate.info
index 5a68a07..32dcd52 100644
--- a/core/modules/locale/tests/modules/locale_test_translate/locale_test_translate.info
+++ b/core/modules/locale/tests/modules/locale_test_translate/locale_test_translate.info
@@ -3,6 +3,7 @@ description = Translation test module for locale module testing.
 package = Testing
 version = 1.3
 core = 8.x
+hidden = TRUE
 
 ; Definitions for interface translations.
 interface translation project = locale_test_translate
diff --git a/core/modules/locale/tests/modules/locale_test_translate/locale_test_translate.module b/core/modules/locale/tests/modules/locale_test_translate/locale_test_translate.module
index ede02fb..f4f1972 100644
--- a/core/modules/locale/tests/modules/locale_test_translate/locale_test_translate.module
+++ b/core/modules/locale/tests/modules/locale_test_translate/locale_test_translate.module
@@ -2,5 +2,5 @@
 
 /**
  * @file
- * Simulates a custom module with a local po files.
+ * Simulates a custom module with a local po file.
  */