Remove usage of Tab's |url| property from TabModel.

ios/web/web_state/ui/crw_web_controller.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/web/web_state/ui/crw_web_controller.h"
 
 #import <WebKit/WebKit.h>
 
 #import <objc/runtime.h>
 #include <stddef.h>
@@ skipping 2860 matching lines @@
 }
 
 - (void)didStartLoadingURL:(const GURL&)URL {
   _loadPhase = web::PAGE_LOADING;
   _URLOnStartLoading = URL;
   _displayStateOnStartLoading = self.pageDisplayState;
 
   self.userInteractionRegistered = NO;
   _pageHasZoomed = NO;
 
-  [[self sessionController] commitPendingItem];
+  self.navigationManagerImpl->CommitPendingItem();
 }
 
 - (void)wasShown {
   if ([self.nativeController respondsToSelector:@selector(wasShown)]) {
     [self.nativeController wasShown];
   }
 }
 
 - (void)wasHidden {
   if (_isHalted)
@@ skipping 2340 matching lines @@
 - (NSUInteger)observerCount {
   DCHECK_EQ(_observerBridges.size(), [_observers count]);
   return [_observers count];
 }
 
 - (NSString*)referrerFromNavigationAction:(WKNavigationAction*)action {
   return [action.request valueForHTTPHeaderField:kReferrerHeaderName];
 }
 
 @end