Remove the concept of currentItemIndex

ios/web/navigation/navigation_manager_impl.h

 // Copyright 2013 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.
 
 #ifndef IOS_WEB_NAVIGATION_NAVIGATION_MANAGER_IMPL_H_
 #define IOS_WEB_NAVIGATION_NAVIGATION_MANAGER_IMPL_H_
 
 #include <stddef.h>
 
 #include <memory>
@@ skipping 106 matching lines @@
   NavigationItem* GetLastCommittedItem() const override;
   NavigationItem* GetPendingItem() const override;
   NavigationItem* GetTransientItem() const override;
   void DiscardNonCommittedItems() override;
   void LoadIfNecessary() override;
   void LoadURLWithParams(const NavigationManager::WebLoadParams&) override;
   void AddTransientURLRewriter(
       BrowserURLRewriter::URLRewriter rewriter) override;
   int GetItemCount() const override;
   NavigationItem* GetItemAtIndex(size_t index) const override;
-  int GetCurrentItemIndex() const override;
   int GetPendingItemIndex() const override;
   int GetLastCommittedItemIndex() const override;
   bool RemoveItemAtIndex(int index) override;
   bool CanGoBack() const override;
   bool CanGoForward() const override;
   bool CanGoToOffset(int offset) const override;
   void GoBack() override;
   void GoForward() override;
   void GoToIndex(int index) override;
   void Reload(ReloadType reload_type, bool check_for_reposts) override;
@@ skipping 55 matching lines @@
   // List of transient url rewriters added by |AddTransientURLRewriter()|.
   std::unique_ptr<std::vector<BrowserURLRewriter::URLRewriter>>
       transient_url_rewriters_;
 
   DISALLOW_COPY_AND_ASSIGN(NavigationManagerImpl);
 };
 
 }  // namespace web
 
 #endif  // IOS_WEB_NAVIGATION_NAVIGATION_MANAGER_IMPL_H_