Bug 1861516 - Remove Translations useFastText pref r=gregtatum

Removes the browser.translations.languageIdentification.useFastText
pref, making CLD2 the only option for language identification
for Translations.

Differential Revision: https://phabricator.services.mozilla.com/D192656

modules/libpref/init/all.js

@@ -3627,13 +3627,6 @@ pref("browser.translations.simulateUnsupportedEngine", false);
 pref("browser.translations.chaos.errors", false);
 pref("browser.translations.chaos.timeoutMS", 0);
 
-// A pref to manage the use of fastText for language detection in Translations.
-// The feature was initially built using fastText, but we are now putting it
-// behind a pref while we investigate some performance improvements.
-// In the meantime, we will use CLD2, which is already available in tree.
-// See https://bugzilla.mozilla.org/show_bug.cgi?id=1836974
-pref("browser.translations.languageIdentification.useFastText", false);
-
 // When a user cancels this number of authentication dialogs coming from
 // a single web page in a row, all following authentication dialogs will
 // be blocked (automatically canceled) for that page. The counter resets

toolkit/components/translations/actors/AboutTranslationsChild.sys.mjs

@@ -2,8 +2,6 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
-
 const lazy = {};
 
 ChromeUtils.defineLazyGetter(lazy, "console", () => {
@@ -18,12 +16,6 @@ ChromeUtils.defineESModuleGetters(lazy, {
     "resource://gre/modules/translation/LanguageDetector.sys.mjs",
 });
 
-XPCOMUtils.defineLazyPreferenceGetter(
-  lazy,
-  "useFastTextPref",
-  "browser.translations.languageIdentification.useFastText"
-);
-
 /**
  * @typedef {import("./TranslationsChild.sys.mjs").LanguageIdEngine} LanguageIdEngine
  * @typedef {import("./TranslationsChild.sys.mjs").TranslationsEngine} TranslationsEngine
@@ -276,20 +268,6 @@ export class AboutTranslationsChild extends JSWindowActorChild {
    * @returns {Promise<{ langTag: string, confidence: number }>}
    */
   AT_identifyLanguage(message) {
-    if (lazy.useFastTextPref) {
-      if (!this.languageIdEngine) {
-        const { Promise, Error } = this.contentWindow;
-        return Promise.reject(
-          new Error("The language identification was not created.")
-        );
-      }
-
-      return this.#convertToContentPromise(
-        this.languageIdEngine
-          .identifyLanguage(message)
-          .then(data => Cu.cloneInto(data, this.contentWindow))
-      );
-    }
     return this.#convertToContentPromise(
       lazy.LanguageDetector.detectLanguage(message).then(data =>
         Cu.cloneInto(

toolkit/components/translations/actors/TranslationsChild.sys.mjs

@@ -78,16 +78,6 @@ export class TranslationsChild extends JSWindowActorChild {
         }
 
         try {
-          // Try to use the fastText engine if directed to do so.
-          if (data.useFastText) {
-            const engine = await this.getOrCreateLanguageIdEngine();
-            if (!engine) {
-              return null;
-            }
-            return engine.identifyLanguageFromDocument(this.document);
-          }
-
-          // Use the CLD2 language detector otherwise.
           return lazy.LanguageDetector.detectLanguageFromDocument(
             this.document
           );

toolkit/components/translations/actors/TranslationsParent.sys.mjs

@@ -120,12 +120,6 @@ XPCOMUtils.defineLazyPreferenceGetter(
   "browser.translations.simulateUnsupportedEngine"
 );
 
-XPCOMUtils.defineLazyPreferenceGetter(
-  lazy,
-  "useFastTextPref",
-  "browser.translations.languageIdentification.useFastText"
-);
-
 // At this time the signatures of the files are not being checked when they are being
 // loaded from disk. This signature check involves hitting the network, and translations
 // are explicitly an offline-capable feature. See Bug 1827265 for re-enabling this
@@ -2161,9 +2155,7 @@ export class TranslationsParent extends JSWindowActorParent {
     ) {
       return null;
     }
-    return this.sendQuery("Translations:IdentifyLanguage", {
-      useFastText: lazy.useFastTextPref,
-    }).catch(error => {
+    return this.sendQuery("Translations:IdentifyLanguage").catch(error => {
       if (this.#isDestroyed) {
         // The actor was destroyed while this message was still being resolved.
         return null;

toolkit/components/translations/tests/browser/browser_about_translations_translations.js

@@ -179,7 +179,6 @@ add_task(async function test_about_translations_language_identification() {
       { fromLang: "en", toLang: "fr" },
       { fromLang: "fr", toLang: "en" },
     ],
-    prefs: [["browser.translations.languageIdentification.useFastText", true]],
     runInPage: async ({ selectors }) => {
       const { document, window } = content;
       Cu.waiveXrays(window).DEBOUNCE_DELAY = 5; // Make the timer run faster for tests.

toolkit/components/translations/tests/browser/browser_translations_full_page.js

@@ -101,7 +101,6 @@ add_task(async function test_language_identification_for_page_translation() {
     detectedLangTag: "es",
     detectedLanguageConfidence: 0.95,
     resolveLanguageIdDownloads: true,
-    prefs: [["browser.translations.languageIdentification.useFastText", true]],
     languagePairs: [
       { fromLang: "es", toLang: "en" },
       { fromLang: "en", toLang: "es" },