1 files changed, 38 insertions, 0 deletions
diff --git a/browser/extensions/pictureinpicture/video-wrappers/airmozilla.js b/browser/extensions/pictureinpicture/video-wrappers/airmozilla.js
new file mode 100644
index 0000000000..db4f97a829
--- /dev/null
+++ b/browser/extensions/pictureinpicture/video-wrappers/airmozilla.js
@@ -0,0 +1,38 @@
+/* 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/. */
+
+"use strict";
+
+class PictureInPictureVideoWrapper {
+  setCaptionContainerObserver(video, updateCaptionsFunction) {
+    let container = document.querySelector("#absoluteControls");
+
+    if (container) {
+      updateCaptionsFunction("");
+      const callback = function(mutationsList, observer) {
+        let text = container?.querySelector("#overlayCaption").innerText;
+
+        if (!text) {
+          updateCaptionsFunction("");
+          return;
+        }
+
+        updateCaptionsFunction(text);
+      };
+
+      // immediately invoke the callback function to add subtitles to the PiP window
+      callback([1], null);
+
+      let captionsObserver = new MutationObserver(callback);
+
+      captionsObserver.observe(container, {
+        attributes: false,
+        childList: true,
+        subtree: true,
+      });
+    }
+  }
+}
+
+this.PictureInPictureVideoWrapper = PictureInPictureVideoWrapper;