1 files changed, 58 insertions, 0 deletions
diff --git a/browser/components/messagepreview/actors/AboutMessagePreviewChild.sys.mjs b/browser/components/messagepreview/actors/AboutMessagePreviewChild.sys.mjs
new file mode 100644
index 0000000000..15c100328b
--- /dev/null
+++ b/browser/components/messagepreview/actors/AboutMessagePreviewChild.sys.mjs
@@ -0,0 +1,58 @@
+/* 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/. */
+
+import { AppConstants } from "resource://gre/modules/AppConstants.sys.mjs";
+
+export class AboutMessagePreviewChild extends JSWindowActorChild {
+  handleEvent(event) {
+    console.log(`Received page event ${event.type}`);
+  }
+
+  actorCreated() {
+    this.exportFunctions();
+  }
+
+  exportFunctions() {
+    if (this.contentWindow) {
+      for (const name of ["MPShowMessage", "MPIsEnabled", "MPShouldShowHint"]) {
+        Cu.exportFunction(this[name].bind(this), this.contentWindow, {
+          defineAs: name,
+        });
+      }
+    }
+  }
+
+  /**
+   * Check if the Message Preview feature is enabled. This reflects the value of
+   * the pref `browser.newtabpage.activity-stream.asrouter.devtoolsEnabled`.
+   *
+   * @returns {boolean}
+   */
+  MPIsEnabled() {
+    return Services.prefs.getBoolPref(
+      "browser.newtabpage.activity-stream.asrouter.devtoolsEnabled",
+      false
+    );
+  }
+
+  /**
+   * Route a message to the parent process to be displayed with the relevant
+   * messaging surface.
+   *
+   * @param {object} message
+   */
+  MPShowMessage(message) {
+    this.sendAsyncMessage(`MessagePreview:SHOW_MESSAGE`, message);
+  }
+
+  /**
+   * Check if a hint should be shown about how to enable Message Preview. The
+   * hint is only displayed in local/unofficial builds.
+   *
+   * @returns {boolean}
+   */
+  MPShouldShowHint() {
+    return !this.MPIsEnabled() && !AppConstants.MOZILLA_OFFICIAL;
+  }
+}