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

ios/chrome/browser/ui/authentication/chrome_signin_view_controller.h

 // Copyright 2015 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_AUTHENTICATION_CHROME_SIGNIN_VIEW_CONTROLLER_H_
 #define IOS_CHROME_BROWSER_UI_AUTHENTICATION_CHROME_SIGNIN_VIEW_CONTROLLER_H_
 
 #import <UIKit/UIKit.h>
 
 #include "components/signin/core/browser/signin_metrics.h"
@@ skipping 42 matching lines @@
 // This marks the end of the sign-in flow.
 - (void)didAcceptSignIn:(ChromeSigninViewController*)controller
          executeCommand:(GenericChromeCommand*)command;
 
 @end
 
 // ChromeSigninViewController is a view controller that handles all the
 // sign-in UI flow.
 @interface ChromeSigninViewController : UIViewController
 
-@property(nonatomic, assign) id<ChromeSigninViewControllerDelegate> delegate;
+@property(nonatomic, weak) id<ChromeSigninViewControllerDelegate> delegate;
 
 // Data clearing policy to use during the authentication.
 // It is valid to set this in the |willStartSignIn:| method of the delegate.
 @property(nonatomic, assign) ShouldClearData shouldClearData;
 
 // Designated initializer.
 // * |browserState| is the current browser state.
 // * |isPresentedOnSettings| indicates whether the settings view controller is
 //   part of the presented view controllers stack.
 // * |accessPoint| represents the access point that initiated the sign-in.
@@ skipping 24 matching lines @@
 
 // Secondary button title used to skip the sign-in.
 @property(nonatomic, readonly) NSString* skipSigninButtonTitle;
 
 @property(nonatomic, readonly) UIButton* primaryButton;
 @property(nonatomic, readonly) UIButton* secondaryButton;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_AUTHENTICATION_CHROME_SIGNIN_VIEW_CONTROLLER_H_