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

ios/chrome/browser/ui/side_swipe/history_side_swipe_provider.mm

Index: ios/chrome/browser/ui/side_swipe/history_side_swipe_provider.mm
diff --git a/ios/chrome/browser/ui/side_swipe/history_side_swipe_provider.mm b/ios/chrome/browser/ui/side_swipe/history_side_swipe_provider.mm
index d23979a63bac4a4f523d2ade6e6815c387838c46..a86e19ff34c876904b013da824f2aa0e31645cd3 100644
--- a/ios/chrome/browser/ui/side_swipe/history_side_swipe_provider.mm
+++ b/ios/chrome/browser/ui/side_swipe/history_side_swipe_provider.mm
@@ -4,9 +4,15 @@
 
 #import "ios/chrome/browser/ui/side_swipe/history_side_swipe_provider.h"
 
+#include "ios/chrome/browser/tabs/tab.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @interface HistorySideSwipeProvider () {
   // Keep a reference to detach before deallocing.
-  TabModel* _tabModel;  // weak
+  __weak TabModel* _tabModel;  // weak
 }
 
 @end