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..0073a2e235fd230f21305b5a6b13ed8a6d5c6b0a 100644
--- a/chrome/browser/resources/settings/languages_page/languages.js
+++ b/chrome/browser/resources/settings/languages_page/languages.js
@@ -121,9 +121,15 @@ Polymer({
       type: Object,
       value: function() { return new Map(); },
     },
+
+    /** @private Prospective UI language when the page was loaded. */
+    originalProspectiveUILanguage_: String,
   },
 
   observers: [
+    // All observers wait for the model to be populated by including the
+    // |languages| property.
+    'prospectiveUILanguageChanged_(prefs.intl.app_locale.value, languages)',
     'preferredLanguagesPrefChanged_(' +
         'prefs.' + preferredLanguagesPrefName + '.value, languages)',
     'spellCheckDictionariesPrefChanged_(' +
@@ -178,6 +184,16 @@ 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 || window.navigator.language;
+          }.bind(this)));
+    }
+
     Promise.all(promises).then(function(results) {
       this.createModel_(results[1], results[2], results[3], results[4]);
       this.resolver_.resolve();
@@ -190,12 +206,22 @@ Polymer({
   },
 
   /**
+   * Updates the prospective UI language based on the new pref value.
+   * @param {string} prospectiveUILanguage
+   * @private
+   */
+  prospectiveUILanguageChanged_: function(prospectiveUILanguage) {
+    this.set('languages.prospectiveUILanguage',
+        prospectiveUILanguage || this.originalProspectiveUILanguage_);
+  },
+
+  /**
    * Updates the list of enabled languages from the preferred languages pref.
    * @private
    */
   preferredLanguagesPrefChanged_: function() {
-    var enabledLanguageStates =
-        this.getEnabledLanguageStates_(this.languages.translateTarget);
+    var enabledLanguageStates = this.getEnabledLanguageStates_(
+        this.languages.translateTarget, this.languages.prospectiveUILanguage);
 
     // Recreate the enabled language set before updating languages.enabled.
     this.enabledLanguageSet_.clear();
@@ -226,8 +252,10 @@ Polymer({
         /** @type {!Array<string>} */(translateBlockedPref.value));
 
     for (var i = 0; i < this.languages.enabled.length; i++) {
-      if (this.languages.enabled[i].language.code == navigator.language)
+      if (this.languages.enabled[i].language.code ==
+          this.languages.prospectiveUILanguage) {
         continue;
+      }
       var translateCode = this.convertLanguageCodeForTranslate(
           this.languages.enabled[i].language.code);
       this.set(
@@ -277,8 +305,16 @@ Polymer({
       }
     }
 
+    var prospectiveUILanguage;
+    if (cr.isChromeOS || cr.isWindows) {
+      prospectiveUILanguage =
+          /** @type {string} */(this.getPref('intl.app_locale').value) ||
+          this.originalProspectiveUILanguage_;
+    }
+
     // Create a list of enabled languages from the supported languages.
-    var enabledLanguageStates = this.getEnabledLanguageStates_(translateTarget);
+    var enabledLanguageStates =
+        this.getEnabledLanguageStates_(translateTarget, prospectiveUILanguage);
     // Populate the hash set of enabled languages.
     for (var languageState of enabledLanguageStates)
       this.enabledLanguageSet_.add(languageState.language.code);
@@ -288,6 +324,10 @@ Polymer({
       enabled: enabledLanguageStates,
       translateTarget: translateTarget,
     });
+
+    if (cr.isChromeOS || cr.isWindows)
+      model.prospectiveUILanguage = prospectiveUILanguage;
+
     if (cr.isChromeOS) {
       model.inputMethods = /** @type {!InputMethodsModel} */({
         supported: supportedInputMethods,
@@ -305,10 +345,12 @@ Polymer({
    * languages list.
    * @param {string} translateTarget Language code of the default translate
    *     target language.
+   * @param {(string|undefined)} prospectiveUILanguage Prospective UI display
+   *     language. Only defined on Windows and Chrome OS.
    * @return {!Array<!LanguageState>}
    * @private
    */
-  getEnabledLanguageStates_: function(translateTarget) {
+  getEnabledLanguageStates_: function(translateTarget, prospectiveUILanguage) {
     assert(CrSettingsPrefs.isInitialized);
 
     var pref = this.getPref(preferredLanguagesPrefName);
@@ -334,10 +376,11 @@ Polymer({
       // Translate is considered disabled if this language maps to any translate
       // language that is blocked.
       var translateCode = this.convertLanguageCodeForTranslate(code);
-      languageState.translateEnabled = !!language.supportsTranslate &&
-          code != navigator.language &&
+      languageState.translateEnabled =
+          !!language.supportsTranslate &&
           !translateBlockedSet.has(translateCode) &&
-          translateCode != translateTarget;
+          translateCode != translateTarget &&
+          (!prospectiveUILanguage || code != prospectiveUILanguage);
       enabledLanguageStates.push(languageState);
     }
     return enabledLanguageStates;
@@ -426,26 +469,18 @@ 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]);
-  },
-
-  /** Resets the prospective UI language back to the actual UI language. */
-  resetUILanguage: function() {
-    assert(cr.isChromeOS || cr.isWindows);
-    chrome.send('setUILanguage', [navigator.language]);
+    chrome.send('setProspectiveUILanguage', [languageCode]);
   },
 
   /**
-   * 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 +541,7 @@ 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.