Converts parts of ios/web to ARC

ios/web/interstitials/web_interstitial_impl.mm

 // Copyright 2015 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/interstitials/web_interstitial_impl.h"
 
 #include "base/logging.h"
 #include "ios/web/interstitials/web_interstitial_facade_delegate.h"
 #include "ios/web/navigation/crw_session_controller.h"
 #include "ios/web/navigation/navigation_manager_impl.h"
 #include "ios/web/public/interstitials/web_interstitial_delegate.h"
 #import "ios/web/public/navigation_manager.h"
 #include "ios/web/web_state/web_state_impl.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace web {
 
 // static
 WebInterstitial* WebInterstitial::GetWebInterstitial(web::WebState* web_state) {
   return web_state->GetWebInterstitial();
 }
 
 WebInterstitialImpl::WebInterstitialImpl(WebStateImpl* web_state,
                                          bool new_navigation,
                                          const GURL& url)
@@ skipping 74 matching lines @@
 
 void WebInterstitialImpl::WebStateDestroyed() {
   DontProceed();
 }
 
 WebStateImpl* WebInterstitialImpl::GetWebStateImpl() const {
   return static_cast<web::WebStateImpl*>(web_state());
 }
 
 }  // namespace web