Revert of [ObjC ARC] Converts ios/chrome/browser/ui/bookmarks:bookmarks_arc_2 to ARC.

ios/chrome/browser/ui/bookmarks/bookmark_collection_cells.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_CELLS_H_
 #define IOS_CHROME_BROWSER_UI_BOOKMARKS_BOOKMARK_COLLECTION_CELLS_H_
 
 #import <UIKit/UIKit.h>
 
 namespace bookmark_cell {
@@ skipping 25 matching lines @@
 #pragma mark - Base Classes For Both Device Types
 
 // Abstract base class for cells in the bookmark collection view.
 // Most controllers that use this cell have an "edit" mode that allows users to
 // select multiple bookmarks. When a cell is selected, a translucent overlay
 // is layered on top to change the look of the view.
 // Subclasses should insert new views below the "highlightCover" property.
 // There is also an image and an optional menu button.
 @interface BookmarkCell : UICollectionViewCell<BookmarkImageableView>
 
-@property(nonatomic, strong, readonly) UILabel* titleLabel;
+@property(nonatomic, retain, readonly) UILabel* titleLabel;
 
 + (NSString*)reuseIdentifier;
 
 // Sets the target/selector for the top-right corner button.
 // |action| must take exactly 2 arguments.
 // The first object passed to |action| will be of type BookmarkItemCell.
 // The second will be the view that was tapped on to trigger the action.
 - (void)setButtonTarget:(id)target action:(SEL)action;
 
 // Changes the appearance of the button.
@@ skipping 31 matching lines @@
 - (void)setTitle:(NSString*)title;
 @end
 
 // Blank white header with thin separator line in the bottom.
 @interface BookmarkHeaderSeparatorView : UICollectionReusableView
 + (NSString*)reuseIdentifier;
 + (CGFloat)preferredHeight;
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_BOOKMARKS_BOOKMARK_COLLECTION_CELLS_H_