Componentize component_updater: Move over a bunch of files to the component.

chrome/browser/component_updater/crx_downloader.h

-// 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_CRX_DOWNLOADER_H_
-#define CHROME_BROWSER_COMPONENT_UPDATER_CRX_DOWNLOADER_H_
-
-#include <vector>
-
-#include "base/basictypes.h"
-#include "base/callback.h"
-#include "base/files/file_path.h"
-#include "base/memory/ref_counted.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/threading/thread_checker.h"
-#include "url/gurl.h"
-
-namespace base {
-class SequencedTaskRunner;
-class SingleThreadTaskRunner;
-}
-
-namespace net {
-class URLRequestContextGetter;
-}
-
-namespace component_updater {
-
-// Defines a download interface for downloading components, with retrying on
-// fallback urls in case of errors. This class implements a chain of
-// responsibility design pattern. It can give successors in the chain a chance
-// to handle a download request, until one of them succeeds, or there are no
-// more urls or successors to try. A callback is always called at the end of
-// the download, one time only.
-// When multiple urls and downloaders exists, first all the urls are tried, in
-// the order they are provided in the StartDownload function argument. After
-// that, the download request is routed to the next downloader in the chain.
-// The members of this class expect to be called from the main thread only.
-class CrxDownloader {
- public:
-  struct DownloadMetrics {
-    enum Downloader { kNone = 0, kUrlFetcher, kBits };
-
-    DownloadMetrics();
-
-    GURL url;
-
-    Downloader downloader;
-
-    int error;
-
-    int64 downloaded_bytes;  // -1 means that the byte count is unknown.
-    int64 total_bytes;
-
-    uint64 download_time_ms;
-  };
-
-  // Contains the progress or the outcome of the download.
-  struct Result {
-    Result();
-
-    // Download error: 0 indicates success.
-    int error;
-
-    // Path of the downloaded file if the download was successful.
-    base::FilePath response;
-
-    // Number of bytes actually downloaded, not including the bytes downloaded
-    // as a result of falling back on urls.
-    int64 downloaded_bytes;
-
-    // Number of bytes expected to be downloaded.
-    int64 total_bytes;
-  };
-
-  // The callback fires only once, regardless of how many urls are tried, and
-  // how many successors in the chain of downloaders have handled the
-  // download. The callback interface can be extended if needed to provide
-  // more visibility into how the download has been handled, including
-  // specific error codes and download metrics.
-  typedef base::Callback<void(const Result& result)> DownloadCallback;
-
-  // The callback may fire 0 or many times during a download. Since this
-  // class implements a chain of responsibility, the callback can fire for
-  // different urls and different downloaders. The number of actual downloaded
-  // bytes is not guaranteed to monotonically increment over time.
-  typedef base::Callback<void(const Result& result)> ProgressCallback;
-
-  // Factory method to create an instance of this class and build the
-  // chain of responsibility. |is_background_download| specifies that a
-  // background downloader be used, if the platform supports it.
-  // |url_fetcher_task_runner| should be an IO capable task runner able to
-  // support UrlFetcherDownloader. |background_task_runner| should be an
-  // IO capable thread able to support BackgroundDownloader.
-  static CrxDownloader* Create(
-      bool is_background_download,
-      net::URLRequestContextGetter* context_getter,
-      scoped_refptr<base::SequencedTaskRunner> url_fetcher_task_runner,
-      scoped_refptr<base::SingleThreadTaskRunner> background_task_runner);
-  virtual ~CrxDownloader();
-
-  void set_progress_callback(const ProgressCallback& progress_callback);
-
-  // Starts the download. One instance of the class handles one download only.
-  // One instance of CrxDownloader can only be started once, otherwise the
-  // behavior is undefined. The callback gets invoked if the download can't
-  // be started.
-  void StartDownloadFromUrl(const GURL& url,
-                            const DownloadCallback& download_callback);
-  void StartDownload(const std::vector<GURL>& urls,
-                     const DownloadCallback& download_callback);
-
-  const std::vector<DownloadMetrics> download_metrics() const;
-
- protected:
-  explicit CrxDownloader(scoped_ptr<CrxDownloader> successor);
-
-  // Handles the fallback in the case of multiple urls and routing of the
-  // download to the following successor in the chain. Derived classes must call
-  // this function after each attempt at downloading the urls provided
-  // in the StartDownload function.
-  // In case of errors, |is_handled| indicates that a server side error has
-  // occured for the current url and the url should not be retried down
-  // the chain to avoid DDOS of the server. This url will be removed from the
-  // list of url and never tried again.
-  void OnDownloadComplete(bool is_handled,
-                          const Result& result,
-                          const DownloadMetrics& download_metrics);
-
-  // Calls the callback when progress is made.
-  void OnDownloadProgress(const Result& result);
-
-  // Returns the url which is currently being downloaded from.
-  GURL url() const;
-
- private:
-  virtual void DoStartDownload(const GURL& url) = 0;
-
-  base::ThreadChecker thread_checker_;
-
-  std::vector<GURL> urls_;
-  scoped_ptr<CrxDownloader> successor_;
-  DownloadCallback download_callback_;
-  ProgressCallback progress_callback_;
-
-  std::vector<GURL>::iterator current_url_;
-
-  std::vector<DownloadMetrics> download_metrics_;
-
-  DISALLOW_COPY_AND_ASSIGN(CrxDownloader);
-};
-
-}  // namespace component_updater
-
-#endif  // CHROME_BROWSER_COMPONENT_UPDATER_CRX_DOWNLOADER_H_