Create distiller files for Reading List.

ios/chrome/browser/reading_list/url_downloader_unittest.mm

 // Copyright 2016 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.
 
 #include "ios/chrome/browser/reading_list/url_downloader.h"
 
 #include <vector>
 
 #include "base/files/file_util.h"
 #import "base/mac/bind_objc_block.h"
@@ skipping 22 matching lines @@
       const dom_distiller::DistilledArticleProto* article_proto) override {}
 
   void SendJavaScript(const std::string& buffer) override {}
 };
 
 }  // namespace
 
 class MockURLDownloader : public URLDownloader {
  public:
   MockURLDownloader(base::FilePath path)
-      : URLDownloader(nil,
-                      nil,
+      : URLDownloader(nullptr,
+                      nullptr,
+                      nullptr,
                       path,
                       base::Bind(&MockURLDownloader::OnEndDownload,
                                  base::Unretained(this)),
                       base::Bind(&MockURLDownloader::OnEndRemove,
                                  base::Unretained(this))) {}
 
   void RemoveOfflineFilesDirectory() {
     base::DeleteFile(reading_list::OfflineRootDirectoryPath(base_directory_),
                      true);
   }
@@ skipping 128 matching lines @@
   ASSERT_TRUE(std::find(downloader_->downloaded_files_.begin(),
                         downloader_->downloaded_files_.end(),
                         url) != downloader_->downloaded_files_.end());
   ASSERT_TRUE(std::find(downloader_->removed_files_.begin(),
                         downloader_->removed_files_.end(),
                         url) != downloader_->removed_files_.end());
   ASSERT_TRUE(downloader_->CheckExistenceOfOfflineURLPagePath(url));
 }
 
 }  // namespace