Polish the cleaning up url request code for parallel download.

content/browser/download/download_job.h

 // 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.
 
 #ifndef CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_JOB_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_JOB_H_
 
 #include "base/macros.h"
 #include "base/time/time.h"
 #include "content/browser/byte_stream.h"
@@ skipping 28 matching lines @@
   // Or return nullptr if the download is not associated with an active
   // WebContents.
   virtual WebContents* GetWebContents() const = 0;
 
   // Returns whether the download is parallelizable. The download may not send
   // parallel requests as it can be disabled through flags.
   virtual bool IsParallelizable() const;
 
   // Cancel a particular request starts from |offset|, while the download is not
   // canceled. Used in parallel download.
+  // TODO(xingliu): Remove this function if download job owns download file.
   virtual void CancelRequestWithOffset(int64_t offset);
 
  protected:
   void StartDownload() const;
   void Interrupt(DownloadInterruptReason reason);
 
   // Add a byte stream to the download sink. Return false if we start to
   // destroy download file.
   bool AddByteStream(std::unique_ptr<ByteStreamReader> stream_reader,
                      int64_t offset,
                      int64_t length);
 
   // Sets the potential length of the file.
   void SetPotentialFileLength(int64_t length);
 
   DownloadItemImpl* download_item_;
 
  private:
   // If the download progress is paused by the user.
   bool is_paused_;
 
   DISALLOW_COPY_AND_ASSIGN(DownloadJob);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_JOB_H_