Added member data to classes to support download resumption.

content/browser/download/download_resource_handler.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_RESOURCE_HANDLER_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_
 #pragma once
 
 #include <string>
 
 #include "base/callback.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/timer.h"
-#include "content/browser/download/download_file.h"
 #include "content/browser/download/download_id.h"
+#include "content/browser/download/download_types.h"
 #include "content/browser/renderer_host/global_request_id.h"
 #include "content/browser/renderer_host/resource_handler.h"
+#include "net/base/net_errors.h"
 
 class DownloadFileManager;
 class ResourceDispatcherHost;
 
 namespace content {
 class DownloadBuffer;
 }
 
 namespace net {
 class URLRequest;
@@ skipping 44 matching lines @@
                                    const std::string& security_info);
   virtual void OnRequestClosed();
 
   // If the content-length header is not present (or contains something other
   // than numbers), the incoming content_length is -1 (unknown size).
   // Set the content length to 0 to indicate unknown size to DownloadManager.
   void set_content_length(const int64& content_length);
 
   void set_content_disposition(const std::string& content_disposition);
 
+  // How many bytes were read before this request was interrupted. Should be
+  // used only by |ResourceDispatcherHost::BeginDownload()|.
+  void set_start_offset(int64 bytes) { start_offset_ = bytes; }

[Randy Smith (Not in Mondays), 2011/11/15 18:45:26]

Can this be in the constructor?  And commented in a way that makes more sense
for this abstraction level?  From the viewpoint of the IO thread/DRH/RDH we're
just executing a request and piping the results across to the FILE & UI threads,
so this would just be "the offset in the resource targeted at which to start
downloading".

+
   void CheckWriteProgress();
 
   std::string DebugString() const;
 
  private:
   virtual ~DownloadResourceHandler();
 
   void StartPauseTimer();
   void CallStartedCB(net::Error error);
 
   DownloadId download_id_;
   GlobalRequestID global_id_;
   int render_view_id_;
   scoped_refptr<net::IOBuffer> read_buffer_;
   std::string content_disposition_;
   int64 content_length_;
   DownloadFileManager* download_file_manager_;
   net::URLRequest* request_;
   bool save_as_;  // Request was initiated via "Save As" by the user.
   OnStartedCallback started_cb_;
   DownloadSaveInfo save_info_;
   scoped_refptr<content::DownloadBuffer> buffer_;
   ResourceDispatcherHost* rdh_;
   bool is_paused_;
   base::OneShotTimer<DownloadResourceHandler> pause_timer_;
   base::TimeTicks download_start_time_;  // used to collect stats.
   base::TimeTicks last_read_time_;        // used to collect stats.
   size_t last_buffer_size_;               // used to collect stats.
+  int64 start_offset_;
   static const int kReadBufSize = 32768;  // bytes
   static const int kThrottleTimeMs = 200;  // milliseconds
 
   DISALLOW_COPY_AND_ASSIGN(DownloadResourceHandler);
 };
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_RESOURCE_HANDLER_H_