Change DownloadProcessHandle to be more of an encapsulated class.

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>
+
+class DownloadManager;
+class ResourceDispatcherHost;
+class TabContents;
+
+// A handle used by the download system for operations on the URLRequest
+// or objects conditional on it (e.g. TabContents).
+// This class needs to be copyable, so we can pass it across threads and not
+// worry about lifetime or const-ness.
+class DownloadRequestHandle {
+ public:
+  // Create a null DownloadRequestHandle: getters will return null, and
+  // all actions are no-ops.
+  // TODO(rdsmith): Ideally, actions would be forbidden rather than
+  // no-ops, to confirm that no non-testing code actually uses
+  // a null DownloadRequestHandle.  But for now, we need the no-op
+  // behavior for unit tests.  Long-term, this should be fixed by
+  // allowing mocking of ResourceDispatcherHost in unit tests.
+  DownloadRequestHandle();
+
+  // 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.
+  void PauseRequest();
+  void ResumeRequest();
+
+  // Cancel the request
+  void CancelRequest();
+
+  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_