Glue parallel download job and download file together.

content/browser/download/download_worker.cc

 // Copyright 2017 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 "content/browser/download/download_worker.h"
 
 #include "content/browser/download/download_create_info.h"
 #include "content/public/browser/download_interrupt_reasons.h"
 #include "content/public/browser/web_contents.h"
 
@@ skipping 14 matching lines @@
                                                    params.get());
 
   return std::unique_ptr<UrlDownloader, BrowserThread::DeleteOnIOThread>(
       UrlDownloader::BeginDownload(delegate, std::move(url_request),
                                    params->referrer())
           .release());
 }
 
 }  // namespace
 
-DownloadWorker::DownloadWorker() : weak_factory_(this) {}
+DownloadWorker::DownloadWorker(DownloadWorker::Delegate* delegate,
+                               int64_t offset,
+                               int64_t length)
+    : delegate_(delegate),
+      offset_(offset),
+      length_(length),
+      weak_factory_(this) {}
 
 DownloadWorker::~DownloadWorker() = default;
 
 void DownloadWorker::SendRequest(
     std::unique_ptr<DownloadUrlParameters> params) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   BrowserThread::PostTaskAndReplyWithResult(
       BrowserThread::IO, FROM_HERE,
       base::Bind(&CreateUrlDownloader, base::Passed(&params),
                  weak_factory_.GetWeakPtr()),
@@ skipping 24 matching lines @@
   // request.
   if (create_info->result !=
       DownloadInterruptReason::DOWNLOAD_INTERRUPT_REASON_NONE) {
     VLOG(kVerboseLevel) << "Parallel download sub request failed. reason = "
                         << create_info->result;
     NOTIMPLEMENTED();
     return;
   }
 
   request_handle_ = std::move(create_info->request_handle);
+  if (delegate_)
+    delegate_->OnByteStreamReady(this, std::move(stream_reader));
 }
 
 void DownloadWorker::OnUrlDownloaderStopped(UrlDownloader* downloader) {
   // Release the |url_downloader_|, the object will be deleted on IO thread.
   url_downloader_.reset();
 }
 
 void DownloadWorker::AddUrlDownloader(
     std::unique_ptr<UrlDownloader, BrowserThread::DeleteOnIOThread>
         downloader) {
   url_downloader_ = std::move(downloader);
 }
 
 }  // namespace content