Removes the IsReadingListEnabled flags

ios/chrome/browser/tabs/tab_helper_util.mm

 // Copyright 2017 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_helper_util.h"
 
 #if !defined(__has_feature) || !__has_feature(objc_arc)
 #error "This file requires ARC support."
 #endif
 
 #import "components/favicon/ios/web_favicon_driver.h"
 #include "components/history/core/browser/top_sites.h"
 #import "components/history/ios/browser/web_state_top_sites_observer.h"
 #include "components/keyed_service/core/service_access_type.h"
-#include "components/reading_list/core/reading_list_switches.h"
 #import "components/signin/ios/browser/account_consistency_service.h"
 #include "ios/chrome/browser/bookmarks/bookmark_model_factory.h"
 #include "ios/chrome/browser/browser_state/chrome_browser_state.h"
 #include "ios/chrome/browser/favicon/favicon_service_factory.h"
 #import "ios/chrome/browser/find_in_page/find_tab_helper.h"
 #include "ios/chrome/browser/history/history_service_factory.h"
 #include "ios/chrome/browser/history/top_sites_factory.h"
 #import "ios/chrome/browser/infobars/infobar_manager_impl.h"
 #include "ios/chrome/browser/reading_list/reading_list_model_factory.h"
 #import "ios/chrome/browser/reading_list/reading_list_web_state_observer.h"
@@ skipping 23 matching lines @@
 
   NetworkActivityIndicatorTabHelper::CreateForWebState(web_state, tab.tabId);
   IOSChromeSyncedTabDelegate::CreateForWebState(web_state);
   InfoBarManagerImpl::CreateForWebState(web_state);
   IOSSecurityStateTabHelper::CreateForWebState(web_state);
   RepostFormTabHelper::CreateForWebState(web_state);
   BlockedPopupTabHelper::CreateForWebState(web_state);
   FindTabHelper::CreateForWebState(web_state, tab.findInPageControllerDelegate);
   StoreKitTabHelper::CreateForWebState(web_state);
 
-  if (reading_list::switches::IsReadingListEnabled()) {
-    ReadingListModel* model =
-        ReadingListModelFactory::GetForBrowserState(browser_state);
-    ReadingListWebStateObserver::FromWebState(web_state, model);
-  }
+  ReadingListModel* model =
+      ReadingListModelFactory::GetForBrowserState(browser_state);
+  ReadingListWebStateObserver::FromWebState(web_state, model);
 
   if (AccountConsistencyService* account_consistency_service =
           ios::AccountConsistencyServiceFactory::GetForBrowserState(
               browser_state)) {
     account_consistency_service->SetWebStateHandler(web_state, tab);
   }
   ChromeIOSTranslateClient::CreateForWebState(web_state);
 
   ios::ChromeBrowserState* original_browser_state =
       browser_state->GetOriginalChromeBrowserState();
   favicon::WebFaviconDriver::CreateForWebState(
       web_state,
       ios::FaviconServiceFactory::GetForBrowserState(
           original_browser_state, ServiceAccessType::IMPLICIT_ACCESS),
       ios::HistoryServiceFactory::GetForBrowserState(
           original_browser_state, ServiceAccessType::IMPLICIT_ACCESS),
       ios::BookmarkModelFactory::GetForBrowserState(original_browser_state));
   history::WebStateTopSitesObserver::CreateForWebState(
       web_state,
       ios::TopSitesFactory::GetForBrowserState(original_browser_state).get());
 
   // Allow the embedder to attach tab helpers.
   ios::GetChromeBrowserProvider()->AttachTabHelpers(web_state, tab);
 }