Removes the IsReadingListEnabled flags

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 23 matching lines @@
 #include "components/history/core/browser/history_service.h"
 #include "components/history/core/browser/top_sites.h"
 #include "components/history/ios/browser/web_state_top_sites_observer.h"
 #include "components/infobars/core/infobar_manager.h"
 #include "components/keyed_service/core/service_access_type.h"
 #include "components/metrics_services_manager/metrics_services_manager.h"
 #include "components/navigation_metrics/navigation_metrics.h"
 #include "components/navigation_metrics/origins_seen_service.h"
 #include "components/prefs/pref_service.h"
 #include "components/reading_list/core/reading_list_model.h"
-#include "components/reading_list/core/reading_list_switches.h"
 #include "components/search_engines/template_url_service.h"
 #include "components/sessions/core/session_types.h"
 #include "components/sessions/ios/ios_serialized_navigation_builder.h"
 #include "components/signin/core/browser/account_reconcilor.h"
 #include "components/signin/core/browser/signin_metrics.h"
 #import "components/signin/ios/browser/account_consistency_service.h"
 #include "components/strings/grit/components_strings.h"
 #include "components/url_formatter/url_formatter.h"
 #include "ios/chrome/browser/application_context.h"
 #import "ios/chrome/browser/autofill/autofill_controller.h"
@@ skipping 2033 matching lines @@
 
 - (TabModel*)parentTabModel {
   return parentTabModel_;
 }
 
 - (FormInputAccessoryViewController*)inputAccessoryViewController {
   return inputAccessoryViewController_.get();
 }
 
 @end