[ObjC ARC] Converts ios/web:web to ARC.

ios/web/public/web_state/ui/crw_content_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_WEB_PUBLIC_WEB_STATE_UI_CRW_CONTENT_VIEW_H_
 #define IOS_WEB_PUBLIC_WEB_STATE_UI_CRW_CONTENT_VIEW_H_
 
 #import <UIKit/UIKit.h>
 
 // UIViews conforming to CRWScrollableContent (i.e. CRWContentViews) are used
 // to display content within a WebState.
 @protocol CRWScrollableContent<NSObject>
 
 // The scroll view used to display the content.  If |scrollView| is non-nil,
 // it will be used to back the CRWContentViewScrollViewProxy and is expected to
 // be a subview of the CRWContentView.
-@property(nonatomic, retain, readonly) UIScrollView* scrollView;
+@property(nonatomic, strong, readonly) UIScrollView* scrollView;
 
 // Adds a top padding to content view. Implementations of this protocol can
 // implement this method using UIScrollView.contentInset (where applicable) or
 // via resizing a subview's frame. Can be used as a workaround for WKWebView
 // bug, where UIScrollView.content inset does not work (rdar://23584409).
 @property(nonatomic, assign) CGFloat topContentPadding;
 
 // Returns YES if content is being displayed in the scroll view.
 // TODO(stuartmorgan): See if this can be removed from the public interface.
 - (BOOL)isViewAlive;
 
 @optional
 
 // Whether or not the content view should use the content inset when setting
 // |topContentPadding|.
 @property(nonatomic, assign) BOOL shouldUseInsetForTopPadding;
 
 @end
 
 // Convenience type for content views.
 typedef UIView<CRWScrollableContent> CRWContentView;
 
 #endif  // IOS_WEB_PUBLIC_WEB_STATE_UI_CRW_CONTENT_VIEW_H_