[iOS] Finalize session restore when committing item

This CL makes sure to call FinalizeSessionRestore when resetting the
restored_visible_item when an item is being committed.

Fixed: 1127434
Change-Id: Idb6ca7ed3a2267dd5343b471c67251c756c8387c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2421113Reviewed-by: Justin Cohen <justincohen@chromium.org>
Reviewed-by: Ali Juma <ajuma@chromium.org>
Commit-Queue: Gauthier Ambard <gambard@chromium.org>
Cr-Commit-Position: refs/heads/master@{#812014}

ios/web/navigation/wk_based_navigation_manager_impl.mm

@@ -83,8 +83,16 @@ void WKBasedNavigationManagerImpl::OnNavigationItemCommitted() {
   DCHECK(item);
   delegate_->OnNavigationItemCommitted(item);
 
-  if (!wk_navigation_util::IsRestoreSessionUrl(item->GetURL()))
+  if (!wk_navigation_util::IsRestoreSessionUrl(item->GetURL())) {
     restored_visible_item_.reset();
+    if (is_restore_session_in_progress_) {
+      // There are crashes because restored_visible_item_ is nil and
+      // is_restore_session_in_progress_ is true. This is a speculative fix,
+      // based on the idea that a navigation item could be committed before
+      // OnNavigationStarted is called. See crbug.com/1127434.
+      FinalizeSessionRestore();
+    }
+  }
 }
 
 void WKBasedNavigationManagerImpl::OnNavigationStarted(const GURL& url) {