Added DownloadProcessHandle class.

chrome/browser/download/download_process_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_PROCESS_HANDLE_H_
+#define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_PROCESS_HANDLE_H_
+#pragma once
+
+#include <string>
+
+class DownloadManager;
+class ResourceDispatcherHost;
+class TabContents;
+
+// Identifiers associated with the download by related subsystems.
+// This class needs to be copyable, but has non-trivial methods.

[Randy Smith (Not in Mondays), 2011/05/05 20:25:34]

A word about why it needs to be copiable (easy enough to copy to not make worth
tracking lifetime issues, being passed across threads) would be worthwhile here.

[ahendrickson, 2011/05/06 16:16:50]

Done.

+class DownloadProcessHandle {
+ public:
+  DownloadProcessHandle();
+  DownloadProcessHandle(int child_id, int render_view_id, int request_id);
+
+  void CancelDownload(ResourceDispatcherHost* rdh);
+  TabContents* GetTabContents();
+  DownloadManager* GetDownloadManager();
+
+  int child_id() const { return child_id_; }

[Randy Smith (Not in Mondays), 2011/05/05 20:25:34]

I'd like to look closely at all places where these accessors are used.  I
suspect it would require very little extra work to make them superfluous and
remove them, which really improves the encapsulation of this class.

+  int render_view_id() const { return render_view_id_; }
+  int request_id() const { return request_id_; }
+
+ private:
+  // 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_PROCESS_HANDLE_H_