Remove the concept of currentItemIndex

ios/web/public/navigation_manager.h

Index: ios/web/public/navigation_manager.h
diff --git a/ios/web/public/navigation_manager.h b/ios/web/public/navigation_manager.h
index 2fd5e061d0cd3ae768c87751f7fa871d74dd730d..75b1201337cd7d2f5bac54e5cb8e8189fb60e27f 100644
--- a/ios/web/public/navigation_manager.h
+++ b/ios/web/public/navigation_manager.h
@@ -120,10 +120,6 @@ class NavigationManager {
   // Returns the committed NavigationItem at |index|.
   virtual NavigationItem* GetItemAtIndex(size_t index) const = 0;
 
-  // Returns the index from which web would go back/forward or reload.
-  // TODO(crbug.com/533848): Update to return size_t.
-  virtual int GetCurrentItemIndex() const = 0;
-
   // Returns the index of the last committed item or -1 if the last
   // committed item correspond to a new navigation.
   // TODO(crbug.com/533848): Update to return size_t.