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

ios/chrome/browser/ui/history/tab_history_cell.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_HISTORY_TAB_HISTORY_CELL_H_
 #define IOS_CHROME_BROWSER_UI_HISTORY_TAB_HISTORY_CELL_H_
 
 #import <UIKit/UIKit.h>
 
 @class CRWSessionEntry;
 
 // Table cell used in TabHistoryViewController.
 @interface TabHistoryCell : UICollectionViewCell
-@property(nonatomic, retain) CRWSessionEntry* entry;
-@property(nonatomic, readonly) UILabel* titleLabel;
+@property(strong, nonatomic) CRWSessionEntry* entry;
+@property(weak, nonatomic, readonly) UILabel* titleLabel;
 @end
 
 // Header for a section of TabHistoryCells.
 @interface TabHistorySectionHeader : UICollectionReusableView
-@property(nonatomic, readonly) UIImageView* iconView;
-@property(nonatomic, readonly) UIView* lineView;
+@property(weak, nonatomic, readonly) UIImageView* iconView;
+@property(weak, nonatomic, readonly) UIView* lineView;
 @end
 
 // Footer for a section of TabHistoryCells.
 @interface TabHistorySectionFooter : UICollectionReusableView
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_HISTORY_TAB_HISTORY_CELL_H_