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

ios/chrome/browser/ui/bookmarks/bookmark_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_COLLECTION_VIEW_H_
 #define IOS_CHROME_BROWSER_UI_BOOKMARKS_BOOKMARK_COLLECTION_VIEW_H_
 
 #import <UIKit/UIKit.h>
 
 #include <set>
@@ skipping 195 matching lines @@
 // just reload relevant cells.
 - (void)cancelAllFaviconLoads;
 
 // Asynchronously loads favicon for given index path. The loads are cancelled
 // upon cell reuse automatically.
 - (void)loadFaviconAtIndexPath:(NSIndexPath*)indexPath;
 
 #pragma mark - Commonly used properties
 
 @property(nonatomic, assign, readonly) bookmarks::BookmarkModel* bookmarkModel;
-@property(nonatomic, assign, readonly) id<UrlLoader> loader;
+@property(nonatomic, weak, readonly) id<UrlLoader> loader;
 @property(nonatomic, assign, readonly) ios::ChromeBrowserState* browserState;
 
 #pragma mark - Editing
 
 @property(nonatomic, assign, readonly) BOOL editing;
 
 #pragma mark - Promo Cell
 
 // Return true if the section at the given index is a promo section.
 - (BOOL)isPromoSection:(NSInteger)section;
 - (BOOL)shouldShowPromoCell;
 - (BOOL)isPromoActive;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_BOOKMARKS_BOOKMARK_COLLECTION_VIEW_H_