Cleaned up old navigation code that did not use pending navigation item.

ios/chrome/browser/tabs/tab.mm

 // Copyright 2012 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/chrome/browser/tabs/tab.h"
 
 #import <CoreLocation/CoreLocation.h>
 #import <UIKit/UIKit.h>
 
 #include <utility>
@@ skipping 1301 matching lines @@
     DCHECK([self navigationManager]);
     [self navigationManager]->DiscardNonCommittedItems();
     // Ensure the UI reflects the current entry, not the just-discarded pending
     // entry.
     [parentTabModel_ notifyTabChanged:self];
     return YES;
   }
   return NO;
 }
 
-- (void)webWillFinishHistoryNavigation {
-  [parentTabModel_ notifyTabChanged:self];
-}
-
 - (void)webState:(web::WebState*)webState
     didFinishNavigation:(web::NavigationContext*)navigation {
   if (navigation->IsSameDocument()) {
     auto* faviconDriver = favicon::WebFaviconDriver::FromWebState(webState);
     if (faviconDriver) {
       // Fetch the favicon for the new URL.
       faviconDriver->FetchFavicon(navigation->GetUrl());
     }
   }
 
@@ skipping 768 matching lines @@
 
 - (TabModel*)parentTabModel {
   return parentTabModel_;
 }
 
 - (FormInputAccessoryViewController*)inputAccessoryViewController {
   return inputAccessoryViewController_.get();
 }
 
 @end