Add control to use If-Range header for range request.

content/browser/download/download_request_core.h

 // Copyright (c) 2012 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_REQUEST_CORE_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_REQUEST_CORE_H_
 
 #include <stddef.h>
 #include <stdint.h>
 
@@ skipping 104 matching lines @@
   net::URLRequest* request() const { return request_; }
 
  private:
   static DownloadInterruptReason HandleRequestStatus(
       const net::URLRequestStatus& status);
 
   static DownloadInterruptReason HandleSuccessfulServerResponse(
       const net::HttpResponseHeaders& http_headers,
       DownloadSaveInfo* save_info);
 
+  static void AddPartialRequestHeaders(net::URLRequest* request,
+                                       DownloadUrlParameters* params);
+
   std::unique_ptr<DownloadCreateInfo> CreateDownloadCreateInfo(
       DownloadInterruptReason result);
 
   Delegate* delegate_;
   net::URLRequest* request_;
 
   // "Passthrough" fields. These are only kept here so that they can be used to
   // populate the DownloadCreateInfo when the time comes.
   std::unique_ptr<DownloadSaveInfo> save_info_;
   uint32_t download_id_;
@@ skipping 29 matching lines @@
 
   // Each successful OnWillRead will yield a buffer of this size.
   static const int kReadBufSize = 32768;   // bytes
 
   DISALLOW_COPY_AND_ASSIGN(DownloadRequestCore);
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_REQUEST_CORE_H_