In onLayoutChange, only scroll if the view is shown and the content v…

…iew is ready

Summary:
ScrollViews don't properly maintain position where they are hidden and shown. When a ScrollView's content is laid out, onLayoutChange is triggered. This is also fired when the views are hidden, which is not desirable as the layout may not be accurate when the view is hidden. Check that the scroll view is showing before attempting a scroll.

Changelog:
[Internal][Fixed] - In onLayoutChange, only scroll if the view is shown and the content view is ready

Reviewed By: sshic

Differential Revision: D42808119

fbshipit-source-id: 0197ae55fa7d80e52c2ea483609e62d512a117f3

ReactAndroid/src/main/java/com/facebook/react/views/scroll/ReactScrollView.java

@@ -1127,10 +1127,12 @@ public void onLayoutChange(
       mMaintainVisibleContentPositionHelper.updateScrollPosition();
     }
 
-    int currentScrollY = getScrollY();
-    int maxScrollY = getMaxScrollY();
-    if (currentScrollY > maxScrollY) {
-      scrollTo(getScrollX(), maxScrollY);
+    if (isShown() && isContentReady()) {
+      int currentScrollY = getScrollY();
+      int maxScrollY = getMaxScrollY();
+      if (currentScrollY > maxScrollY) {
+        scrollTo(getScrollX(), maxScrollY);
+      }
     }
   }