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

ios/chrome/browser/ui/stack_view/stack_view_controller.h

 // Copyright 2012 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_STACK_VIEW_STACK_VIEW_CONTROLLER_H_
 #define IOS_CHROME_BROWSER_UI_STACK_VIEW_STACK_VIEW_CONTROLLER_H_
 
 #import <UIKit/UIKit.h>
 
 #import "ios/chrome/browser/ui/tab_switcher/tab_switcher.h"
@@ skipping 10 matching lines @@
 - (void)stackViewControllerShowWithSelectedTabAnimationDidStart;
 // Informs the delegate that the show tab animation finished.
 - (void)stackViewControllerShowWithSelectedTabAnimationDidEnd;
 // Informs the delegate that the preload of card views finished.
 - (void)stackViewControllerPreloadCardViewsDidEnd;
 @end
 
 // Controller for the tab-switching UI displayed as a stack of tabs.
 @interface StackViewController : UIViewController<TabSwitcher>
 
-@property(nonatomic, assign) id<TabSwitcherDelegate> delegate;
-@property(nonatomic, assign) id<StackViewControllerTestDelegate> testDelegate;
+@property(nonatomic, weak) id<TabSwitcherDelegate> delegate;
+@property(nonatomic, weak) id<StackViewControllerTestDelegate> testDelegate;
 
 // Initializes with the given tab models, which must not be nil.
 // |activeTabModel| is the model which starts active, and must be one of the
 // other two models.
 // TODO(stuartmorgan): Replace the word 'active' in these methods and the
 // corresponding delegate methods. crbug.com/513782
 - (instancetype)initWithMainTabModel:(TabModel*)mainModel
                          otrTabModel:(TabModel*)otrModel
                       activeTabModel:(TabModel*)activeModel;
 
@@ skipping 27 matching lines @@
 // |position| with |transition|. Otherwise, simply returns nil.
 // If |position| == NSNotFound the tab will be added at the end of the stack.
 - (Tab*)dismissWithNewTabAnimationToModel:(TabModel*)targetModel
                                   withURL:(const GURL&)url
                                   atIndex:(NSUInteger)position
                                transition:(ui::PageTransition)transition;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_STACK_VIEW_STACK_VIEW_CONTROLLER_H_