Fix race condition in MD Settings Languages page causing inconsistent settings

chrome/common/extensions/api/language_settings_private.idl

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Use the <code>chrome.languageSettingsPrivate</code> API to get or change
 // language and input method settings.
 namespace languageSettingsPrivate {
   dictionary Language {
     // The unique code identifying the language.
     DOMString code;
@@ skipping 62 matching lines @@
   callback GetInputMethodListsCallback = void (InputMethodLists lists);
   callback GetSpellcheckWordsCallback = void (DOMString[] words);
   callback GetTranslateTargetLanguageCallback = void (DOMString languageCode);
   callback GetSpellcheckDictionaryStatusesCallback =
       void (SpellcheckDictionaryStatus[] status);
 
   interface Functions {
     // Gets languages available for translate, spell checking, input and locale.
     static void getLanguageList(GetLanguageListCallback callback);
 
-    // Sets the accepted languages, used to decide which languages to translate,
-    // generate the Accept-Language header, etc.
-    static void setLanguageList(DOMString[] languageCodes);
+    // Enables a language, adding it to the Accept-Language list (used to decide
+    // which languages to translate, generate the Accept-Language header, etc.).
+    static void enableLanguage(DOMString languageCode);
+
+    // Disables a language, removing it from the Accept-Language list.
+    static void disableLanguage(DOMString languageCode);
 
     // Gets the current status of the chosen spell check dictionaries.
     static void getSpellcheckDictionaryStatuses(
         GetSpellcheckDictionaryStatusesCallback callback);
 
     // Gets the custom spell check words, in sorted order.
     static void getSpellcheckWords(GetSpellcheckWordsCallback callback);
 
     // Adds a word to the custom dictionary.
     static void addSpellcheckWord(DOMString word);
@@ skipping 29 matching lines @@
     static void onCustomDictionaryChanged(
         DOMString[] wordsAdded, DOMString[] wordsRemoved);
 
     // Called when an input method is added.
     static void onInputMethodAdded(DOMString inputMethodId);
 
     // Called when an input method is removed.
     static void onInputMethodRemoved(DOMString inputMethodId);
   };
 };