[ObjC ARC] Converts components/reading_list/ios:ios to ARC.

components/reading_list/ios/reading_list_model_bridge_observer.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 "components/reading_list/ios/reading_list_model_bridge_observer.h"
 
 #include "components/reading_list/core/reading_list_entry.h"
 #include "components/reading_list/core/reading_list_model.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 ReadingListModelBridge::ReadingListModelBridge(
     id<ReadingListModelBridgeObserver> observer,
     ReadingListModel* model)
     : observer_(observer), model_(model) {
   DCHECK(model);
   model_->AddObserver(this);
 }
 
 ReadingListModelBridge::~ReadingListModelBridge() {
   if (model_) {
@@ skipping 83 matching lines @@
 }
 
 void ReadingListModelBridge::ReadingListWillUpdateEntry(
     const ReadingListModel* model,
     const GURL& url) {
   if ([observer_
           respondsToSelector:@selector(readingListModel:willUpdateEntry:)]) {
     [observer_ readingListModel:model willUpdateEntry:url];
   }
 }