Revert "Revert "[Refactoring] Intersection Observer: Revert redundant workaround for freezing""

This reverts commit 55d7648698917aa9c51d4a4e5ca18b8433a968bd.

src/components/middle/hooks/useMessageObservers.ts

@@ -31,7 +31,6 @@ export default function useMessageObservers(
   } = useIntersectionObserver({
     rootRef: containerRef,
     throttleMs: INTERSECTION_THROTTLE_FOR_READING,
-    noAutoFreeze: true,
   }, (entries) => {
     if (type !== 'thread') {
       return;

src/hooks/useIntersectionObserver.ts

@@ -22,8 +22,6 @@ interface Response {
   unfreeze: NoneToVoidFunction;
 }
 
-const AUTO_UNFREEZE_TIMEOUT = 2000;
-
 export function useIntersectionObserver({
   rootRef,
   throttleMs,
@@ -32,7 +30,6 @@ export function useIntersectionObserver({
   margin,
   threshold,
   isDisabled,
-  noAutoFreeze = false,
 }: {
   rootRef: RefObject<HTMLDivElement>;
   throttleMs?: number;
@@ -41,16 +38,18 @@ export function useIntersectionObserver({
   margin?: number;
   threshold?: number | number[];
   isDisabled?: boolean;
-  noAutoFreeze?: boolean;
 }, rootCallback?: RootCallback): Response {
   const controllerRef = useRef<IntersectionController>();
   const rootCallbackRef = useRef<RootCallback>();
   const freezeFlagsRef = useRef(0);
-  const autoUnfreezeTimeoutRef = useRef<number>();
   const onUnfreezeRef = useRef<NoneToVoidFunction>();
 
   rootCallbackRef.current = rootCallback;
 
+  const freeze = useCallback(() => {
+    freezeFlagsRef.current++;
+  }, []);
+
   const unfreeze = useCallback(() => {
     if (!freezeFlagsRef.current) {
       return;
@@ -64,31 +63,6 @@ export function useIntersectionObserver({
     }
   }, []);
 
-  const freeze = useCallback(() => {
-    freezeFlagsRef.current++;
-
-    if (noAutoFreeze) {
-      return;
-    }
-
-    if (autoUnfreezeTimeoutRef.current) {
-      clearTimeout(autoUnfreezeTimeoutRef.current);
-      autoUnfreezeTimeoutRef.current = undefined;
-    }
-
-    // Make sure to unfreeze even if unfreeze callback was not called (which was some hardly-reproducible bug)
-    autoUnfreezeTimeoutRef.current = window.setTimeout(() => {
-      autoUnfreezeTimeoutRef.current = undefined;
-
-      if (!freezeFlagsRef.current) {
-        return;
-      }
-
-      freezeFlagsRef.current = 1;
-      unfreeze();
-    }, AUTO_UNFREEZE_TIMEOUT);
-  }, [noAutoFreeze, unfreeze]);
-
   useHeavyAnimationCheck(freeze, unfreeze);
 
   useEffect(() => {