fix: optimize scroll position observer after video fullscreen exit

Author: ihor-romaniuk

src/courseware/course/sequence/Unit/hooks/useIFrameBehavior.js

@@ -50,19 +50,19 @@ const useIFrameBehavior = ({
     if (type === messageTypes.resize) {
       setIframeHeight(payload.height);
 
-      // We observe exit from the video xblock fullscreen mode
-      // and scroll to the previously saved scroll position
-      if (windowTopOffset !== null) {
-        window.scrollTo(0, Number(windowTopOffset));
-      }
-
       if (!hasLoaded && iframeHeight === 0 && payload.height > 0) {
         setHasLoaded(true);
         if (onLoaded) {
           onLoaded();
         }
       }
     } else if (type === messageTypes.videoFullScreen) {
+      // We observe exit from the video xblock fullscreen mode
+      // and scroll to the previously saved scroll position
+      if (!payload.open && windowTopOffset !== null) {
+        window.scrollTo(0, Number(windowTopOffset));
+      }
+
       // We listen for this message from LMS to know when we need to
       // save or reset scroll position on toggle video xblock fullscreen mode
       setWindowTopOffset(payload.open ? window.scrollY : null);