Language settings: Fix Restart and Remove buttons shown at wrong times

chrome/browser/resources/settings/languages_page/languages.js

Index: chrome/browser/resources/settings/languages_page/languages.js
diff --git a/chrome/browser/resources/settings/languages_page/languages.js b/chrome/browser/resources/settings/languages_page/languages.js
index 790a45fba91d763cbad5c548833d0bc05dae1fdb..dc54735a4dbb90a3de07c02b77e377630a05aee3 100644
--- a/chrome/browser/resources/settings/languages_page/languages.js
+++ b/chrome/browser/resources/settings/languages_page/languages.js
@@ -121,9 +121,13 @@ Polymer({
       type: Object,
       value: function() { return new Map(); },
     },
+
+    /** @private Prospective UI language when the page was loaded. */
+    originalProspectiveUILanguage_: String,
   },
 
   observers: [
+    'prospectiveUILanguageChanged_(prefs.intl.app_locale.value)',
     'preferredLanguagesPrefChanged_(' +
         'prefs.' + preferredLanguagesPrefName + '.value, languages)',
     'spellCheckDictionariesPrefChanged_(' +
@@ -178,6 +182,16 @@ Polymer({
       }.bind(this));
     }
 
+    if (cr.isWindows || cr.isChromeOS) {
+      // Fetch the starting UI language, which affects which actions should be
+      // enabled.
+      promises.push(cr.sendWithPromise('getProspectiveUILanguage').then(
+          function(prospectiveUILanguage) {
+            this.originalProspectiveUILanguage_ =
+                prospectiveUILanguage || navigator.language;
+          }.bind(this)));
+    }
+
     Promise.all(promises).then(function(results) {
       this.createModel_(results[1], results[2], results[3], results[4]);
       this.resolver_.resolve();
@@ -190,6 +204,19 @@ Polymer({
   },
 
   /**
+   * Updates the prospective UI languages based on the new pref value.
+   * @param {string} prospectiveUILanguage
+   * @private
+   */
+  prospectiveUILanguageChanged_: function(prospectiveUILanguage) {
+    if (!this.languages)
+      return;
+
+    this.set('languages.prospectiveUILanguage',
+        prospectiveUILanguage || this.originalProspectiveUILanguage_);
+  },
+
+  /**
    * Updates the list of enabled languages from the preferred languages pref.
    * @private
    */
@@ -288,6 +315,11 @@ Polymer({
       enabled: enabledLanguageStates,
       translateTarget: translateTarget,
     });
+    if (cr.isChromeOS || cr.isWindows) {
+      model.prospectiveUILanguage =
+          /** @type {string} */(this.getPref('intl.app_locale').value) ||
+          this.originalProspectiveUILanguage_;
+    }
     if (cr.isChromeOS) {
       model.inputMethods = /** @type {!InputMethodsModel} */({
         supported: supportedInputMethods,
@@ -426,26 +458,25 @@ Polymer({
    * the actual UI language until a restart.
    * @param {string} languageCode
    */
-  setUILanguage: function(languageCode) {
+  setProspectiveUILanguage: function(languageCode) {
     assert(cr.isChromeOS || cr.isWindows);
-    chrome.send('setUILanguage', [languageCode]);
+    chrome.send('setProspectiveUILanguage', [languageCode]);
   },
 
   /** Resets the prospective UI language back to the actual UI language. */
-  resetUILanguage: function() {
+  resetProspectiveUILanguage: function() {
     assert(cr.isChromeOS || cr.isWindows);
-    chrome.send('setUILanguage', [navigator.language]);
+    chrome.send(
+        'setProspectiveUILanguage', [this.originalProspectiveUILanguage_]);
   },
 
   /**
-   * Returns the "prospective" UI language, i.e. the one to be used on next
-   * restart. If the pref is not set, the current UI language is also the
-   * "prospective" language.
-   * @return {string} Language code of the prospective UI language.
+   * True if the prospective UI language was changed from its starting value.
+   * @return {boolean}
    */
-  getProspectiveUILanguage: function() {
-    return /** @type {string} */(this.getPref('intl.app_locale').value) ||
-        navigator.language;
+  requiresRestart: function() {
+    return this.originalProspectiveUILanguage_ !=
+        this.languages.prospectiveUILanguage;
   },
 
   /**
@@ -506,7 +537,7 @@ Polymer({
    */
   canDisableLanguage: function(languageCode) {
     // Cannot disable the prospective UI language.
-    if (languageCode == this.getProspectiveUILanguage())
+    if (languageCode == this.languages.prospectiveUILanguage)
       return false;
 
     // Cannot disable the only enabled language.