Added member data to classes to support download resumption.

content/browser/download/download_types.h

 // Copyright (c) 2011 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_TYPES_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_TYPES_H_
 #pragma once
 
 #include "base/file_path.h"
 #include "base/memory/linked_ptr.h"
 #include "content/common/content_export.h"
 #include "net/base/file_stream.h"
 
 // Holds the information about how to save a download file.
+// In the case of download continuation, |file_path| is set to the current file
+// name, |offset| is set to the point where we left off, and |hash_state| will
+// hold the state of the hash algorithm where we left off.
 struct CONTENT_EXPORT DownloadSaveInfo {
   DownloadSaveInfo();
   DownloadSaveInfo(const DownloadSaveInfo& info);
   ~DownloadSaveInfo();
   DownloadSaveInfo& operator=(const DownloadSaveInfo& info);
 
+  // This is usually the tentative final name, but not during resumption
+  // where it will be the intermediate file name.
   FilePath file_path;
+
   linked_ptr<net::FileStream> file_stream;
+
   string16 suggested_name;
+
+  // The file offset at which to start the download.  May be 0.
+  int64 offset;
+
+  // The state of the hash at the start of the download.  May be empty.
+  std::string hash_state;
 };
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_TYPES_H_