Implement a background downloader using BITS in Windows Chrome.

chrome/browser/component_updater/background_downloader_win.h

Index: chrome/browser/component_updater/background_downloader_win.h
diff --git a/chrome/browser/component_updater/background_downloader_win.h b/chrome/browser/component_updater/background_downloader_win.h
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+// Copyright 2013 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_COMPONENT_UPDATER_BACKGROUND_DOWNLOADER_WIN_H_
+#define CHROME_BROWSER_COMPONENT_UPDATER_BACKGROUND_DOWNLOADER_WIN_H_
+
+#include "chrome/browser/component_updater/crx_downloader.h"
+
+#include <windows.h>
+#include <bits.h>
+
+#include "base/strings/string16.h"
+#include "base/timer/timer.h"
+#include "base/win/scoped_comptr.h"
+
+namespace component_updater {
+
+// Implements a downloader in terms of the BITS service. The public interface
+// of this class and the CrxDownloader overrides are expected to be called
+// from the UI thread. The rest of the class code runs on the FILE thread in
+// a single threaded apartment.
+class BackgroundDownloader : public CrxDownloader {
+ protected:
+  friend class CrxDownloader;
+  BackgroundDownloader(scoped_ptr<CrxDownloader> successor,
+                       net::URLRequestContextGetter* context_getter,
+                       scoped_refptr<base::SequencedTaskRunner> task_runner,
+                       const DownloadCallback& download_callback);
+  virtual ~BackgroundDownloader();
+
+ private:
+  // Overrides for CrxDownloader.
+  virtual void DoStartDownload(const GURL& url) OVERRIDE;
+
+  // Called asynchronously on the FILE thread at different stages during
+  // the download. |OnDownloading| can be called multiple times.
+  void BeginDownload(const GURL& url);
+  void OnDownloading();
+  void EndDownload(HRESULT hr);
+
+  // Handles the job state transitions to a final state.
+  void OnStateTransferred();
+  void OnStateError();
+  void OnStateCancelled();
+  void OnStateAcknowledged();
+
+  HRESULT QueueBitsJob(const GURL& url);
+  HRESULT CreateOrOpenJob(const GURL& url);
+  HRESULT InitializeNewJob(const GURL& url);
+
+  static HRESULT CleanupStaleJobs(
+    base::win::ScopedComPtr<IBackgroundCopyManager> bits_manager);
+
+  net::URLRequestContextGetter* context_getter_;
+  scoped_refptr<base::SequencedTaskRunner> task_runner_;
+
+  scoped_ptr<base::RepeatingTimer<BackgroundDownloader> > timer_;
+
+  base::win::ScopedComPtr<IBackgroundCopyManager> bits_manager_;
+  base::win::ScopedComPtr<IBackgroundCopyJob> job_;
+
+  bool is_completed_;
+
+  DISALLOW_COPY_AND_ASSIGN(BackgroundDownloader);
+};
+
+}  // namespace component_updater
+
+#endif  // CHROME_BROWSER_COMPONENT_UPDATER_BACKGROUND_DOWNLOADER_WIN_H_
+