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

ios/chrome/browser/ui/history/tab_history_cell.h

Index: ios/chrome/browser/ui/history/tab_history_cell.h
diff --git a/ios/chrome/browser/ui/history/tab_history_cell.h b/ios/chrome/browser/ui/history/tab_history_cell.h
index 365ce4b0d5e9c0635eeffa856ee33a2ec00d9ff4..745a9d5d4230e0b66ed77924fc9b2671aedd9ca4 100644
--- a/ios/chrome/browser/ui/history/tab_history_cell.h
+++ b/ios/chrome/browser/ui/history/tab_history_cell.h
@@ -11,14 +11,14 @@
 
 // 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.