[ARC] Converts part of ios/web/public to ARC.

ios/web/web_state/crw_pass_kit_downloader.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/web_state/crw_pass_kit_downloader.h"
 
 #include <memory>
 
 #import "base/ios/weak_nsobject.h"
 #include "base/mac/scoped_block.h"
 #include "base/macros.h"
 #include "base/metrics/histogram.h"
 #include "base/strings/sys_string_conversions.h"
 #import "ios/web/crw_network_activity_indicator_manager.h"
 #include "net/http/http_response_headers.h"
 #include "net/url_request/url_fetcher.h"
 #include "net/url_request/url_fetcher_delegate.h"
 #include "net/url_request/url_request_context_getter.h"
 
+#if !defined(__has_feature) || !__has_feature(objc_arc)
+#error "This file requires ARC support."
+#endif
+
 using net::URLFetcher;
 using net::URLFetcherDelegate;
 using net::URLRequestContextGetter;
 
 namespace {
 
 // Key of the UMA Download.IOSDownloadPassKitResult histogram.
 const char kUMADownloadPassKitResult[] = "Download.IOSDownloadPassKitResult";
 
 // Enum for the Download.IOSDownloadPassKitResult UMA histogram to report the
@@ skipping 87 matching lines @@
 }
 
 - (instancetype)init {
   NOTREACHED();
   return nil;
 }
 
 - (void)dealloc {
   [[CRWNetworkActivityIndicatorManager sharedInstance]
       clearNetworkTasksForGroup:[self networkActivityKey]];
-  [super dealloc];
 }
 
 - (BOOL)isMIMETypePassKitType:(NSString*)MIMEType {
   return [MIMEType isEqualToString:@"application/vnd.apple.pkpass"];
 }
 
 - (void)downloadPassKitFileWithURL:(const GURL&)URL {
   _fetcher = URLFetcher::Create(URL, URLFetcher::GET, _fetcherDelegate.get());
   _fetcher->SetRequestContext(_requestContextGetter.get());
   CRWNetworkActivityIndicatorManager* sharedManager =
@@ skipping 56 matching lines @@
       stringWithFormat:@"PassKitDownloader.NetworkActivityIndicatorKey.%d",
                        _passKitDownloaderID];
 }
 
 - (void)reportUMAPassKitResult:(DownloadPassKitResult)result {
   UMA_HISTOGRAM_ENUMERATION(kUMADownloadPassKitResult, result,
                             DOWNLOAD_PASS_KIT_RESULT_COUNT);
 }
 
 @end