[Accept Languages List] Check all criteria when updating whether a language can

be translated or not.

Bug: 872096
Change-Id: I9cd2df787c46f6b95f3918adaf8023a030c0b480
Reviewed-on: https://chromium-review.googlesource.com/c/1313416
Commit-Queue: Alexandre Frechette <frechette@chromium.org>
Reviewed-by: Michael Giuffrida <michaelpg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#605744}

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

@@ -392,17 +392,12 @@ Polymer({
         /** @type {!Array<string>} */ (translateBlockedPref.value));
 
     for (let i = 0; i < this.languages.enabled.length; i++) {
-      if (this.languages.enabled[i].language.code ==
-          this.languages.prospectiveUILanguage) {
-        continue;
-      }
-      // This conversion primarily strips away the region part.
-      // For example "fr-CA" --> "fr".
-      const translateCode = this.convertLanguageCodeForTranslate(
-          this.languages.enabled[i].language.code);
+      const language = this.languages.enabled[i].language;
+      const translateEnabled = this.isTranslateEnabled_(
+          language.code, !!language.supportsTranslate, translateBlockedSet,
+          this.languages.translateTarget, this.languages.prospectiveUILanguage);
       this.set(
-          'languages.enabled.' + i + '.translateEnabled',
-          !translateBlockedSet.has(translateCode));
+          'languages.enabled.' + i + '.translateEnabled', translateEnabled);
     }
   },
 
@@ -542,13 +537,9 @@ Polymer({
       const languageState = /** @type {LanguageState} */ ({});
       languageState.language = language;
       languageState.spellCheckEnabled = !!spellCheckSet.has(code);
-      // Translate is considered disabled if this language maps to any translate
-      // language that is blocked.
-      const translateCode = this.convertLanguageCodeForTranslate(code);
-      languageState.translateEnabled = !!language.supportsTranslate &&
-          !translateBlockedSet.has(translateCode) &&
-          translateCode != translateTarget &&
-          (!prospectiveUILanguage || code != prospectiveUILanguage);
+      languageState.translateEnabled = this.isTranslateEnabled_(
+          code, !!language.supportsTranslate, translateBlockedSet,
+          translateTarget, prospectiveUILanguage);
       languageState.isManaged = !!spellCheckForcedSet.has(code);
       languageState.downloadDictionaryFailureCount = 0;
       enabledLanguageStates.push(languageState);
@@ -556,6 +547,29 @@ Polymer({
     return enabledLanguageStates;
   },
 
+  /**
+   * True iff we translate pages that are in the given language.
+   * @param {string} code Language code.
+   * @param {boolean} supportsTranslate If translation supports the given
+   *     language.
+   * @param {!Set<string>} translateBlockedSet Set of languages for which
+   *     translation is blocked.
+   * @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 {boolean}
+   * @private
+   */
+  isTranslateEnabled_: function(
+      code, supportsTranslate, translateBlockedSet, translateTarget,
+      prospectiveUILanguage) {
+    const translateCode = this.convertLanguageCodeForTranslate(code);
+    return supportsTranslate && !translateBlockedSet.has(translateCode) &&
+        translateCode != translateTarget &&
+        (!prospectiveUILanguage || code != prospectiveUILanguage);
+  },
+
   // <if expr="not is_macosx">
   /**
    * Updates the dictionary download status for languages in

chrome/test/data/webui/settings/languages_page_tests.js

@@ -330,6 +330,19 @@ cr.define('languages_page_tests', function() {
         }, settings.kMenuCloseDelay + 1);
       });
 
+      test('toggle translate for target language', function() {
+        // Open options for 'en'.
+        const languageOptionsDropdownTrigger =
+            languagesCollapse.querySelectorAll('button')[0];
+        assertTrue(!!languageOptionsDropdownTrigger);
+        languageOptionsDropdownTrigger.click();
+        assertTrue(actionMenu.open);
+
+        // 'en' does not support.
+        const translateOption = getMenuItem('offerToTranslateInThisLanguage');
+        assertTrue(translateOption.disabled);
+      });
+
       test('disable translate hides language-specific option', function() {
         // Disables translate.
         languageHelper.setPrefValue('translate.enabled', false);