[ios] Use web_state_list in web_contents_mediator.

ios/clean/chrome/browser/ui/tab/tab_coordinator.mm

 // Copyright 2016 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/clean/chrome/browser/ui/tab/tab_coordinator.h"
 
 #include <memory>
 
 #include "base/mac/foundation_util.h"
 #include "base/memory/ptr_util.h"
@@ skipping 34 matching lines @@
 #pragma mark - BrowserCoordinator
 
 - (void)start {
   self.viewController = [self newTabContainer];
   self.viewController.transitioningDelegate = self;
   self.viewController.modalPresentationStyle = UIModalPresentationCustom;
   _webStateObserver =
       base::MakeUnique<web::WebStateObserverBridge>(self.webState, self);
 
   WebCoordinator* webCoordinator = [[WebCoordinator alloc] init];
-  webCoordinator.webState = self.webState;
   [self addChildCoordinator:webCoordinator];
   // Unset the base view controller, so |webCoordinator| doesn't present its
   // view controller.
   webCoordinator.context.baseViewController = nil;
   [webCoordinator start];
 
   ToolbarCoordinator* toolbarCoordinator = [[ToolbarCoordinator alloc] init];
   toolbarCoordinator.webState = self.webState;
   [self addChildCoordinator:toolbarCoordinator];
   // Unset the base view controller, so |toolbarCoordinator| doesn't present
@@ skipping 84 matching lines @@
 - (id<UIViewControllerAnimatedTransitioning>)
 animationControllerForDismissedController:(UIViewController*)dismissed {
   ZoomTransitionAnimator* animator = [[ZoomTransitionAnimator alloc] init];
   animator.presenting = NO;
   animator.presentationKey = self.presentationKey;
   [animator selectDelegate:@[ dismissed.presentingViewController ]];
   return animator;
 }
 
 @end