[ObjC ARC] Converts ios/web/public/test/fakes:fakes to ARC.

ios/web/public/test/fakes/test_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/test/fakes/test_web_view_content_view.h"
 
 #include "base/logging.h"
-#import "base/mac/scoped_nsobject.h"
+
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
 
 @interface TestWebViewContentView () {
-  base::scoped_nsprotocol<id> _mockWebView;
-  base::scoped_nsprotocol<id> _mockScrollView;
+  id _mockWebView;
+  id _mockScrollView;
 }
 
 @end
 
 @implementation TestWebViewContentView
 
 - (instancetype)initWithMockWebView:(id)webView scrollView:(id)scrollView {
   self = [super initForTesting];
   if (self) {
     DCHECK(webView);
     DCHECK(scrollView);
-    _mockWebView.reset([webView retain]);
-    _mockScrollView.reset([scrollView retain]);
+    _mockWebView = webView;
+    _mockScrollView = scrollView;
   }
   return self;
 }
 
 - (instancetype)initWithCoder:(NSCoder*)decoder {
   NOTREACHED();
   return nil;
 }
 
 - (instancetype)initWithFrame:(CGRect)frame {
   NOTREACHED();
   return nil;
 }
 
 #pragma mark Accessors
 
 - (UIScrollView*)scrollView {
-  return static_cast<UIScrollView*>(_mockScrollView.get());
+  return static_cast<UIScrollView*>(_mockScrollView);
 }
 
 - (UIView*)webView {
-  return static_cast<UIView*>(_mockWebView.get());
+  return static_cast<UIView*>(_mockWebView);
 }
 
 @end