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

ios/web/web_state/ui/crw_web_view_content_view.mm

 // 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.
 
 #import "ios/web/public/web_state/ui/crw_web_view_content_view.h"
 
 #import <WebKit/WebKit.h>
 
 #include "base/logging.h"
-
-#if !defined(__has_feature) || !__has_feature(objc_arc)
-#error "This file requires ARC support."
-#endif
+#import "base/mac/scoped_nsobject.h"
 
 namespace {
 
 // Background color RGB values for the content view which is displayed when the
 // |_webView| is offset from the screen due to user interaction. Displaying this
 // background color is handled by UIWebView but not WKWebView, so it needs to be
 // set in CRWWebViewContentView to support both. The color value matches that
 // used by UIWebView.
 const CGFloat kBackgroundRGBComponents[] = {0.75f, 0.74f, 0.76f};
 
 }  // namespace
 
 @interface CRWWebViewContentView () {
+  // The web view being shown.
+  base::scoped_nsobject<UIView> _webView;
+  // The web view's scroll view.
+  base::scoped_nsobject<UIScrollView> _scrollView;
   // Backs up property of the same name if |_webView| is a WKWebView.
   CGFloat _topContentPadding;
 }
 
 // Changes web view frame to match |self.bounds| and optionally accomodates for
 // |_topContentPadding| (iff |_webView| is a WKWebView).
 - (void)updateWebViewFrame;
 
-// The web view being shown.
-@property(nonatomic, strong, readwrite) UIView* webView;
-// The web view's scroll view.
-@property(nonatomic, strong, readwrite) UIScrollView* scrollView;
 @end
 
 @implementation CRWWebViewContentView
 
 @synthesize shouldUseInsetForTopPadding = _shouldUseInsetForTopPadding;
-@synthesize webView = _webView;
-@synthesize scrollView = _scrollView;
 
 - (instancetype)initWithWebView:(UIView*)webView
                      scrollView:(UIScrollView*)scrollView {
   self = [super initWithFrame:CGRectZero];
   if (self) {
     DCHECK(webView);
     DCHECK(scrollView);
     DCHECK([scrollView isDescendantOfView:webView]);
-    _webView = webView;
-    _scrollView = scrollView;
+    _webView.reset([webView retain]);
+    _scrollView.reset([scrollView retain]);
   }
   return self;
 }
 
 - (instancetype)initForTesting {
   return [super initWithFrame:CGRectZero];
 }
 
 - (instancetype)initWithCoder:(NSCoder*)decoder {
   NOTREACHED();
@@ skipping 29 matching lines @@
   [self updateWebViewFrame];
 }
 
 - (void)setBounds:(CGRect)bounds {
   if (CGRectEqualToRect(self.bounds, bounds))
     return;
   [super setBounds:bounds];
   [self updateWebViewFrame];
 }
 
+#pragma mark Accessors
+
+- (UIScrollView*)scrollView {
+  return _scrollView.get();
+}
+
+- (UIView*)webView {
+  return _webView.get();
+}
+
 #pragma mark Layout
 
 - (void)layoutSubviews {
   [super layoutSubviews];
   [self updateWebViewFrame];
 }
 
 - (BOOL)isViewAlive {
   return YES;
 }
@@ skipping 45 matching lines @@
 
 - (void)updateWebViewFrame {
   CGRect webViewFrame = self.bounds;
   webViewFrame.size.height -= _topContentPadding;
   webViewFrame.origin.y += _topContentPadding;
 
   self.webView.frame = webViewFrame;
 }
 
 @end