fix: keep autoplay fallback from saving mute

(cherry picked from commit f373bb9ce7)

js/utils/autoplayPreference.js

@@ -0,0 +1,27 @@
+const FALLBACK_MUTE_DATASET_KEY = "bitvidAutoplayFallbackMute";
+
+/**
+ * Mute playback after an unmuted autoplay rejection without recording the
+ * browser-policy fallback as a viewer preference.
+ */
+export function muteForAutoplayFallback(videoElement) {
+  if (!videoElement || videoElement.muted) {
+    return false;
+  }
+
+  if (videoElement.dataset) {
+    videoElement.dataset[FALLBACK_MUTE_DATASET_KEY] = "true";
+  }
+  videoElement.muted = true;
+  return true;
+}
+
+/** Consume the marker attached to the next fallback-generated volume change. */
+export function consumeAutoplayFallbackMute(videoElement) {
+  if (videoElement?.dataset?.[FALLBACK_MUTE_DATASET_KEY] !== "true") {
+    return false;
+  }
+
+  delete videoElement.dataset[FALLBACK_MUTE_DATASET_KEY];
+  return true;
+}