[ObjC ARC] Converts ios/web:core to ARC.Automatically generated ARCMigrate commitNotable issues:…

ios/web/crw_network_activity_indicator_manager.mm

 // Copyright 2014 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/crw_network_activity_indicator_manager.h"
 
 #import <UIKit/UIKit.h>
 
 #include "base/logging.h"
 #include "base/mac/scoped_nsobject.h"
 #include "base/threading/thread_checker.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 @interface CRWNetworkActivityIndicatorManager () {
   base::scoped_nsobject<NSMutableDictionary> _groupCounts;
   NSUInteger _totalCount;
   base::ThreadChecker _threadChecker;
 }
 
 @end
 
 @implementation CRWNetworkActivityIndicatorManager
 
@@ skipping 80 matching lines @@
   }
   return [number unsignedIntegerValue];
 }
 
 - (NSUInteger)numTotalNetworkTasks {
   DCHECK(_threadChecker.CalledOnValidThread());
   return _totalCount;
 }
 
 @end