Nested virtualized lists should receive recordInteration events

Summary:
Right now when an interaction is recorded on a parent VirtualizedList, the interaction isn't passed on to its children. That means that if `waitForInteraction` is set to true for a child list's viewability helper, it will never trigger a VPV.

This change adds forwarding of these events inside `onBeginScrollDrag`. It also forwards the interaction state of the parent list at register time, in case a child list is rendered mid-scroll.

Reviewed By: sahrens

Differential Revision: D6822091

fbshipit-source-id: dfe300e42722d4285f65787ab2c1368f050c5577

Libraries/Lists/VirtualizedList.js

@@ -375,6 +375,9 @@ class VirtualizedList extends React.PureComponent<Props, State> {
   }
 
   recordInteraction() {
+    this._nestedChildLists.forEach(childList => {
+      childList.ref && childList.ref.recordInteraction();
+    });
     this._viewabilityTuples.forEach(t => {
       t.viewabilityHelper.recordInteraction();
     });
@@ -512,6 +515,10 @@ class VirtualizedList extends React.PureComponent<Props, State> {
       state: null,
     });
 
+    if (this._hasInteracted) {
+      childList.ref.recordInteraction();
+    }
+
     return existingChildData && existingChildData.state;
   };
 
@@ -941,6 +948,7 @@ class VirtualizedList extends React.PureComponent<Props, State> {
   _frames = {};
   _footerLength = 0;
   _hasDataChangedSinceEndReached = true;
+  _hasInteracted = false;
   _hasMore = false;
   _hasWarned = {};
   _highestMeasuredFrameIndex = 0;
@@ -1334,9 +1342,13 @@ class VirtualizedList extends React.PureComponent<Props, State> {
   }
 
   _onScrollBeginDrag = (e): void => {
+    this._nestedChildLists.forEach(childList => {
+      childList.ref && childList.ref._onScrollBeginDrag(e);
+    });
     this._viewabilityTuples.forEach(tuple => {
       tuple.viewabilityHelper.recordInteraction();
     });
+    this._hasInteracted = true;
     this.props.onScrollBeginDrag && this.props.onScrollBeginDrag(e);
   };