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

ios/chrome/browser/ui/bookmarks/bookmark_folder_collection_view.h

 // 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.
 
 #ifndef IOS_CHROME_BROWSER_UI_BOOKMARKS_BOOKMARK_FOLDER_COLLECTION_VIEW_H_
 #define IOS_CHROME_BROWSER_UI_BOOKMARKS_BOOKMARK_FOLDER_COLLECTION_VIEW_H_
 
 #import "ios/chrome/browser/ui/bookmarks/bookmark_collection_view.h"
 
 @class BookmarkFolderCollectionView;
@@ skipping 13 matching lines @@
 // folder transition. Depending on the type of animation that the designers
 // choose, we may require multiple instances of this view.
 @interface BookmarkFolderCollectionView : BookmarkCollectionView
 
 // Refreshes the entire view to reflect |folder|.
 - (void)resetFolder:(const bookmarks::BookmarkNode*)folder;
 
 // Called when something outside the view causes the promo state to change.
 - (void)promoStateChangedAnimated:(BOOL)animate;
 
-@property(nonatomic, assign) id<BookmarkFolderCollectionViewDelegate> delegate;
+@property(nonatomic, weak) id<BookmarkFolderCollectionViewDelegate> delegate;
 @property(nonatomic, assign, readonly) const bookmarks::BookmarkNode* folder;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_BOOKMARKS_BOOKMARK_FOLDER_COLLECTION_VIEW_H_