Change return type of Tab -navigationManager.

ios/chrome/browser/tabs/tab_model.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_model.h"
 
 #include <cstdint>
 #include <utility>
 #include <vector>
 
@@ skipping 722 matching lines @@
   DCHECK([_tabRetainer containsObject:closedTab]);
   int closedTabIndex = _webStateList.GetIndexOfWebState(closedTab.webState);
   DCHECK_NE(closedTabIndex, WebStateList::kInvalidIndex);
   DCHECK_GE(closedTabIndex, 0);
 
   // Let the sessions::TabRestoreService know about that new tab.
   sessions::TabRestoreService* restoreService =
       _browserState
           ? IOSChromeTabRestoreServiceFactory::GetForBrowserState(_browserState)
           : nullptr;
-  web::NavigationManagerImpl* navigationManager = [closedTab navigationManager];
+  web::NavigationManager* navigationManager = [closedTab navigationManager];
   DCHECK(navigationManager);
   int itemCount = navigationManager->GetItemCount();
   if (restoreService && (![self isNTPTab:closedTab] || itemCount > 1)) {
     restoreService->CreateHistoricalTab(
         sessions::IOSLiveTab::GetForWebState(closedTab.webState),
         closedTabIndex);
   }
   // This needs to be called before the tab is removed from the list.
   Tab* newSelection =
       [_orderController determineNewSelectedTabFromRemovedTab:closedTab];
@@ skipping 26 matching lines @@
 }
 
 - (void)navigationCommittedInTab:(Tab*)tab {
   if (self.offTheRecord)
     return;
   if (![tab navigationManager])
     return;
 
   // See if the navigation was within a page; if so ignore it.
   web::NavigationItem* previousItem =
-      [tab navigationManager]->GetPreviousItem();
+      [tab navigationManagerImpl]->GetPreviousItem();
   if (previousItem) {
     GURL previousURL = previousItem->GetURL();
     GURL currentURL = [tab navigationManager]->GetVisibleItem()->GetURL();
 
     url::Replacements<char> replacements;
     replacements.ClearRef();
     if (previousURL.ReplaceComponents(replacements) ==
         currentURL.ReplaceComponents(replacements)) {
       return;
     }
@@ skipping 259 matching lines @@
   web::NavigationManager::WebLoadParams params(URL);
   params.referrer = referrer;
   params.transition_type = ui::PAGE_TRANSITION_TYPED;
   [[tab webController] loadWithParams:params];
   [tab webController].webUsageEnabled = webUsageEnabled_;
   [self insertTab:tab atIndex:index opener:parentTab];
   return tab;
 }
 
 @end