[Empties] Reload content before calculating bookmark promo offset.

In some cases the model and table were not in sync, which caused a
crash when trying to get the visibleCells of the table.

The reload should not be too expensive since we only call it when
we're on the root bookmark page.

Bug: 1116408
Change-Id: I41e3f1c6d09ca5b92f2bbb0494d426e04f2db539
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2370605Reviewed-by: Sergio Collazos <sczs@chromium.org>
Commit-Queue: sebsg <sebsg@chromium.org>
Auto-Submit: sebsg <sebsg@chromium.org>
Cr-Commit-Position: refs/heads/master@{#801008}

ios/chrome/browser/ui/bookmarks/bookmark_home_view_controller.mm

@@ -1472,6 +1472,12 @@ std::vector<GURL> GetUrlsToOpen(const std::vector<const BookmarkNode*>& nodes) {
     // If the Signin promo is visible on the root view, we have to shift the
     // empty TableView background to make it fully visible on all devices.
     if ([self isDisplayingBookmarkRoot]) {
+      // Reload the data to ensure consistency between the model and the table
+      // (an example scenario can be found at crbug.com/1116408). Reloading the
+      // data should only be done for the root bookmark folder since it can be
+      // very expensive in other folders.
+      [self.sharedState.tableView reloadData];
+
       self.navigationItem.largeTitleDisplayMode =
           UINavigationItemLargeTitleDisplayModeNever;
       if (self.sharedState.promoVisible &&