Modified cancel and interrupt processing to avoid race with history.

chrome/browser/download/download_request_handle.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 CHROME_BROWSER_DOWNLOAD_DOWNLOAD_REQUEST_HANDLE_H_
 #define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_REQUEST_HANDLE_H_
 #pragma once
 
 #include <string>
 
@@ skipping 19 matching lines @@
   // Note that |rdh| is required to be non-null.
   DownloadRequestHandle(ResourceDispatcherHost* rdh,
                         int child_id,
                         int render_view_id,
                         int request_id);
 
   // These functions must be called on the UI thread.
   TabContents* GetTabContents() const;
   DownloadManager* GetDownloadManager() const;
 
-  // Pause or resume the matching URL request.
+  // Pause or resume the matching URL request.  Note that while these
+  // do not modify the DownloadRequestHandle, they do modify the
+  // request the handle refers to.
   void PauseRequest() const;
   void ResumeRequest() const;
 
-  // Cancel the request
+  // Cancel the request.  Note that while this does not
+  // modify the DownloadRequestHandle, it does modify the
+  // request the handle refers to.
   void CancelRequest() const;
 
   std::string DebugString() const;
 
  private:
   // The resource dispatcher host.
   ResourceDispatcherHost* rdh_;
 
   // The ID of the child process that started the download.
   int child_id_;
 
   // The ID of the render view that started the download.
   int render_view_id_;
 
   // The ID associated with the request used for the download.
   int request_id_;
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_REQUEST_HANDLE_H_