Don't create parallel request until download file is initialized

content/browser/download/download_job_impl.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_job_impl.h"
 
 #include "content/public/browser/web_contents.h"
 
 namespace content {
 
 DownloadJobImpl::DownloadJobImpl(
     DownloadItemImpl* download_item,
     std::unique_ptr<DownloadRequestHandleInterface> request_handle,
     bool is_parallizable)
     : DownloadJob(download_item),
       request_handle_(std::move(request_handle)),
       is_parallizable_(is_parallizable) {}
 
 DownloadJobImpl::~DownloadJobImpl() = default;
 
-void DownloadJobImpl::Start() {
-  DownloadJob::StartDownload();
-}
-
 void DownloadJobImpl::Cancel(bool user_cancel) {
   if (request_handle_)
     request_handle_->CancelRequest();
 }
 
 void DownloadJobImpl::Pause() {
   DownloadJob::Pause();
   if (request_handle_)
     request_handle_->PauseRequest();
 }
 
 void DownloadJobImpl::Resume(bool resume_request) {
   DownloadJob::Resume(resume_request);
   if (!resume_request)
     return;
 
   if (request_handle_)
     request_handle_->ResumeRequest();
 }
 
 WebContents* DownloadJobImpl::GetWebContents() const {
   return request_handle_ ? request_handle_->GetWebContents() : nullptr;
 }
 
 bool DownloadJobImpl::IsParallelizable() const {
   return is_parallizable_;
 }
 
 }  // namespace content