[ios] [tab_grid] Hide empty state

The empty state needs to be hidden if there are items showing.

Cq-Include-Trybots: luci.chromium.try:ios-simulator-full-configs;master.tryserver.chromium.mac:ios-simulator-cronet
Change-Id: I7feda2eb661b2bda31065eca99eee5445b359601
Reviewed-on: https://chromium-review.googlesource.com/1068259
Reviewed-by: edchin <edchin@chromium.org>
Reviewed-by: Sergio Collazos <sczs@chromium.org>
Commit-Queue: edchin <edchin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#560617}

ios/chrome/browser/ui/tab_grid/grid/grid_view_controller.mm

@@ -111,6 +111,7 @@ - (void)viewWillAppear:(BOOL)animated {
                               scrollPosition:UICollectionViewScrollPositionTop];
   // Update the delegate, in case it wasn't set when |items| was populated.
   [self.delegate gridViewController:self didChangeItemCount:self.items.count];
+  [self animateEmptyStateOut];
 }
 
 - (void)viewDidAppear:(BOOL)animated {