1 files changed, 62 insertions, 0 deletions
diff --git a/toolkit/components/translations/actors/AboutTranslationsParent.sys.mjs b/toolkit/components/translations/actors/AboutTranslationsParent.sys.mjs
new file mode 100644
index 0000000000..4680dbeef5
--- /dev/null
+++ b/toolkit/components/translations/actors/AboutTranslationsParent.sys.mjs
@@ -0,0 +1,62 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * 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/. */
+
+const lazy = {};
+ChromeUtils.defineESModuleGetters(lazy, {
+  TranslationsParent: "resource://gre/actors/TranslationsParent.sys.mjs",
+});
+
+/**
+ * This parent is blank because the Translations actor handles most of the features
+ * needed in AboutTranslations.
+ */
+export class AboutTranslationsParent extends JSWindowActorParent {
+  #isDestroyed = false;
+
+  didDestroy() {
+    this.#isDestroyed = true;
+  }
+
+  async receiveMessage({ name, data }) {
+    switch (name) {
+      case "AboutTranslations:GetTranslationsPort": {
+        const { fromLanguage, toLanguage } = data;
+        const engineProcess = await lazy.TranslationsParent.getEngineProcess();
+        if (this.#isDestroyed) {
+          return undefined;
+        }
+        const { port1, port2 } = new MessageChannel();
+        engineProcess.actor.startTranslation(
+          fromLanguage,
+          toLanguage,
+          port1,
+          this.browsingContext.top.embedderElement.innerWindowID
+        );
+
+        // At the time of writing, you can't return a port via the `sendQuery` API,
+        // so results can't just be returned. The `sendAsyncMessage` method must be
+        // invoked. Additionally, in the AboutTranslationsChild, the port must
+        // be transfered to the content page with `postMessage`.
+        this.sendAsyncMessage(
+          "AboutTranslations:SendTranslationsPort",
+          {
+            fromLanguage,
+            toLanguage,
+            port: port2,
+          },
+          [port2] // Mark the port as transerable.
+        );
+        return undefined;
+      }
+      case "AboutTranslations:GetSupportedLanguages": {
+        return lazy.TranslationsParent.getSupportedLanguages();
+      }
+      case "AboutTranslations:IsTranslationsEngineSupported": {
+        return lazy.TranslationsParent.getIsTranslationsEngineSupported();
+      }
+      default:
+        throw new Error("Unknown AboutTranslations message: " + name);
+    }
+  }
+}