Updated ownership of NavigationItems within CRWSessionController.

ios/web/navigation/navigation_manager_storage_builder.mm

Index: ios/web/navigation/navigation_manager_storage_builder.mm
diff --git a/ios/web/navigation/navigation_manager_storage_builder.mm b/ios/web/navigation/navigation_manager_storage_builder.mm
index 82da72bc3c2d08b047972dce595b66dc0d6726b9..a039ec8753f7a45133d6c7da486121ab928d29f0 100644
--- a/ios/web/navigation/navigation_manager_storage_builder.mm
+++ b/ios/web/navigation/navigation_manager_storage_builder.mm
@@ -54,8 +54,7 @@ @interface CRWSessionController (ExposedForSerialization)
   NSMutableArray* item_storages = [[NSMutableArray alloc] init];
   NavigationItemStorageBuilder item_storage_builder;
   for (size_t index = 0; index < session_controller.items.size(); ++index) {
-    web::NavigationItemImpl* item =
-        static_cast<web::NavigationItemImpl*>(session_controller.items[index]);
+    web::NavigationItemImpl* item = session_controller.items[index].get();
     [item_storages addObject:item_storage_builder.BuildStorage(item)];
   }
   serialized_navigation_manager.itemStorages = item_storages;