Add a new UMA enum to record how many download uses parallel requests

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 22 matching lines @@
 
   bool is_paused() const { return is_paused_; }
 
   // Return the WebContents associated with the download. Usually used to
   // associate a browser window for any UI that needs to be displayed to the
   // user.
   // Or return nullptr if the download is not associated with an active
   // WebContents.
   virtual WebContents* GetWebContents() const = 0;
 
+  // Returns whether the download uses parallel requests.
+  virtual bool UsesParallelRequests() const;
+
  protected:
   void StartDownload() const;
   void Interrupt(DownloadInterruptReason reason);
 
   // Add a byte stream to the download sink.
   void AddByteStream(std::unique_ptr<ByteStreamReader> stream_reader,
                      int64_t offset,
                      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_