Don't create parallel request until download file is initialized

content/browser/download/parallel_download_job.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/parallel_download_job.h"
 
 #include <algorithm>
 
 #include "base/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
@@ skipping 16 matching lines @@
     std::unique_ptr<DownloadRequestHandleInterface> request_handle,
     const DownloadCreateInfo& create_info)
     : DownloadJobImpl(download_item, std::move(request_handle), true),
       initial_request_offset_(create_info.offset),
       content_length_(create_info.total_bytes),
       requests_sent_(false),
       is_canceled_(false) {}
 
 ParallelDownloadJob::~ParallelDownloadJob() = default;
 
-void ParallelDownloadJob::Start() {
-  DownloadJobImpl::Start();
-
-  BuildParallelRequestAfterDelay();
+void ParallelDownloadJob::OnDownloadFileInitialized(
+    const DownloadFile::InitializeCallback& callback,
+    DownloadInterruptReason result) {
+  DownloadJobImpl::OnDownloadFileInitialized(callback, result);
+  if (result == DOWNLOAD_INTERRUPT_REASON_NONE)
+    BuildParallelRequestAfterDelay();
 }
 
 void ParallelDownloadJob::Cancel(bool user_cancel) {
   is_canceled_ = true;
   DownloadJobImpl::Cancel(user_cancel);
 
   if (!requests_sent_) {
     timer_.Stop();
     return;
   }
@@ skipping 177 matching lines @@
   // download request.
   download_params->set_referrer(Referrer(download_item_->GetReferrerUrl(),
                                          blink::kWebReferrerPolicyAlways));
   // Send the request.
   worker->SendRequest(std::move(download_params));
   DCHECK(workers_.find(offset) == workers_.end());
   workers_[offset] = std::move(worker);
 }
 
 }  // namespace content