Remove the concept of currentItemIndex

ios/web/navigation/session_storage_builder.mm

 // Copyright 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import "ios/web/navigation/session_storage_builder.h"
 
 #include "base/logging.h"
 #include "base/mac/foundation_util.h"
 #import "ios/web/navigation/crw_session_controller+private_constructors.h"
 #import "ios/web/navigation/crw_session_controller.h"
@@ skipping 20 matching lines @@
     WebStateImpl* web_state) const {
   DCHECK(web_state);
   web::NavigationManagerImpl* navigation_manager =
       web_state->navigation_manager_.get();
   DCHECK(navigation_manager);
   CRWSessionStorage* session_storage = [[CRWSessionStorage alloc] init];
   session_storage.hasOpener = web_state->HasOpener();
   CRWSessionController* session_controller =
       navigation_manager->GetSessionController();
   session_storage.currentNavigationIndex =
-      session_controller.currentNavigationIndex;
+      session_controller.lastCommittedItemIndex;
   session_storage.previousNavigationIndex =
       session_controller.previousNavigationIndex;
   session_storage.sessionCertificatePolicyManager =
       session_controller.sessionCertificatePolicyManager;
   NSMutableArray* item_storages = [[NSMutableArray alloc] init];
   NavigationItemStorageBuilder item_storage_builder;
   for (size_t index = 0; index < session_controller.items.size(); ++index) {
     web::NavigationItemImpl* item = session_controller.items[index].get();
     [item_storages addObject:item_storage_builder.BuildStorage(item)];
   }
@@ skipping 29 matching lines @@
   [session_controller
       setSessionCertificatePolicyManager:storage
                                              .sessionCertificatePolicyManager];
   web_state->navigation_manager_.reset(new NavigationManagerImpl());
   web_state->navigation_manager_->SetSessionController(session_controller);
   web::SerializableUserDataManager::FromWebState(web_state)
       ->AddSerializableUserData(storage.userData);
 }
 
 }  // namespace web