[ObjC ARC] Converts ios/chrome/browser/ui/bookmarks:bookmarks to ARC.

ios/chrome/browser/ui/bookmarks/bookmark_model_bridge_observer.mm

 // Copyright 2014 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.
 
 #include "ios/chrome/browser/ui/bookmarks/bookmark_model_bridge_observer.h"
 
 #import <Foundation/Foundation.h>
 
 #include "base/logging.h"
 #include "components/bookmarks/browser/bookmark_model.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 namespace bookmarks {
 
 BookmarkModelBridge::BookmarkModelBridge(
     id<BookmarkModelBridgeObserver> observer,
     BookmarkModel* model)
     : observer_(observer), model_(model) {
   DCHECK(observer_);
   DCHECK(model_);
   model_->AddObserver(this);
 }
@@ skipping 58 matching lines @@
   [observer_ bookmarkNodeChildrenChanged:node];
 }
 
 void BookmarkModelBridge::BookmarkAllUserNodesRemoved(
     BookmarkModel* model,
     const std::set<GURL>& removed_urls) {
   [observer_ bookmarkModelRemovedAllNodes];
 }
 
 }  // namespace bookmarks