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

ios/chrome/browser/ui/first_run/welcome_to_chrome_view.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_FIRST_RUN_WELCOME_TO_CHROME_VIEW_H_
 #define IOS_CHROME_BROWSER_UI_FIRST_RUN_WELCOME_TO_CHROME_VIEW_H_
 
 #import <UIKit/UIKit.h>
 
 @class WelcomeToChromeView;
 
 // Delegate for WelcomeToChromeViews.
 @protocol WelcomeToChromeViewDelegate<NSObject>
 
 // Called when the user taps on the "Terms of Service" link.
 - (void)welcomeToChromeViewDidTapTOSLink:(WelcomeToChromeView*)view;
 
 // Called when the user taps the "Accept & Continue" button.
 - (void)welcomeToChromeViewDidTapOKButton:(WelcomeToChromeView*)view;
 
 @end
 
 // The first view shown to the user after fresh installs.
 @interface WelcomeToChromeView : UIView
 
-@property(nonatomic, assign) id<WelcomeToChromeViewDelegate> delegate;
+@property(nonatomic, weak) id<WelcomeToChromeViewDelegate> delegate;
 
 // Whether the stats reporting check box is selected.
 @property(nonatomic, assign, getter=isCheckBoxSelected) BOOL checkBoxSelected;
 
 // Runs the transition animation from Launch Screen to the Welcome to Chrome
 // View. This method must be called after the view is added to a superview and
 // the view's subviews have been laid out.
 - (void)runLaunchAnimation;
 
 @end
 
 #endif  // IOS_CHROME_BROWSER_UI_FIRST_RUN_WELCOME_TO_CHROME_VIEW_H_