Allow the main functionality of ULS to be disabled

Allow the cache-breaking toolbar and cookie-based user language
selection features to be disabled, while still allowing Wikibase to have
its language autocompletion drop-downs on special pages.

Change-Id: Iba18f666fdcf5b87b7068ab6b1537c868c8fe861

UniversalLanguageSelector.hooks.php

@@ -26,6 +26,11 @@ class UniversalLanguageSelectorHooks {
 	 * @return bool
 	 */
 	public static function addModules( $out, $skin ) {
+		global $wgULSEnable;
+		if ( !$wgULSEnable ) {
+			return true;
+		}
+
 		$out->addModules( 'ext.uls.init' );
 		$out->addModules( 'ext.uls.geoclient' );
 
@@ -54,7 +59,11 @@ class UniversalLanguageSelectorHooks {
 	 * Hooks: SkinTemplateNavigation, SkinTemplateTabs
 	 */
 	static function addTrigger( array &$personal_urls, &$title ) {
-		global $wgLang;
+		global $wgULSEnable, $wgLang;
+		if ( !$wgULSEnable ) {
+			return true;
+		}
+
 		$personal_urls = array(
 			'uls' => array(
 				'text' => $wgLang->getLanguageName( $wgLang->getCode() ),
@@ -113,7 +122,11 @@ class UniversalLanguageSelectorHooks {
 	 * @return bool
 	 */
 	public static function getLanguage( $user, &$code ) {
-		global $wgRequest, $wgULSLanguageDetection;
+		global $wgULSEnable, $wgRequest, $wgULSLanguageDetection;
+
+		if ( !$wgULSEnable ) {
+			return true;
+		}
 
 		$languageToSave = $wgRequest->getVal( 'setlang' );
 		if ( $wgRequest->getVal( 'uselang' ) && !$languageToSave ) {

UniversalLanguageSelector.php

@@ -68,6 +68,14 @@ $wgULSIMEEnabled = true;
  */
 $wgULSLanguageDetection = true;
 
+/**
+ * Enable language selection. If language selection is disabled, the classes
+ * and RL modules are registered for the use of other extensions, but no
+ * language selection toolbar is shown, and it will not be possible to change 
+ * the interface language using a cookie.
+ */
+$wgULSEnable = true;
+
 $dir = __DIR__;
 
 // Internationalization