If customization includes default wallpaper, download and apply it.

chrome/browser/chromeos/customization_wallpaper_downloader.h

+// Copyright 2014 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_CHROMEOS_CUSTOMIZATION_WALLPAPER_DOWNLOADER_H_
+#define CHROME_BROWSER_CHROMEOS_CUSTOMIZATION_WALLPAPER_DOWNLOADER_H_
+
+#include <string>
+
+#include "base/bind.h"
+#include "base/files/file_path.h"
+#include "base/macros.h"
+#include "base/memory/weak_ptr.h"
+#include "base/time/time.h"
+#include "base/timer/timer.h"
+#include "chrome/browser/chromeos/customization_document.h"
+#include "net/url_request/url_fetcher.h"
+#include "url/gurl.h"
+
+namespace chromeos {
+
+// Download customized wallpaper.
+// ServicesCustomizationDocument::SetDefaultWallpaperPath() in called on
+// success.
+class CustomizationWallpaperDownloader : public net::URLFetcherDelegate {

[Dmitry Polukhin, 2014/03/27 04:36:32]

It is very sad that we have no code re-use with existing wallpaper manager that
can also download and set user's wallpaper. But I'm not familiar with wallpaper
code so it is unavoidable :(

[Alexander Alekseev, 2014/03/31 14:15:40]

Actually we reuse all possible code from WallpaperManager as it cannot download
wallpapers ;-) User wallpapers are downloaded by extension which is very
specific to the server API and requires active user session.

+ public:
+  CustomizationWallpaperDownloader(
+      net::URLRequestContextGetter* url_context_getter,
+      const GURL& wallpaper_url,
+      const base::FilePath& wallpaper_dir,
+      const base::FilePath& wallpaper_downloaded_file);
+
+  virtual ~CustomizationWallpaperDownloader();
+
+  // Start download.
+  void Start();
+
+  // net::URLFetcherDelegate
+  virtual void OnURLFetchComplete(const net::URLFetcher* source) OVERRIDE;
+
+ private:
+  // Start new request.
+  void StartRequest();
+
+  // Schedules retry.
+  void Retry();
+
+  // Create wallpaper cache directory and analyze result.
+  // Called on BlockingPool.
+  static void CreateWallpaperDirectory(const base::FilePath& wallpaper_dir,
+                                       bool* success);
+  // Called on UI thread.
+  void OnWallpaperDirectoryCreated(scoped_ptr<bool> success);

[Dmitry Polukhin, 2014/03/27 04:36:32]

Why do you need scoped_ptr<bool> again it seems that you can pass what even you
need as parameter without with trick.

[Alexander Alekseev, 2014/03/31 14:15:40]

It's the same: to never pass WeakPointer to other thread.

+
+  // Rename temporary file to wallpaper file and analyze result.
+  // Called on BlockingPool.
+  static void RenameTemporaryFile(const base::FilePath& from,
+                                  const base::FilePath& to,
+                                  bool* success);
+
+  // Called on UI thread.
+  void OnTemporaryFileRenamed(scoped_ptr<bool> success);
+
+  scoped_refptr<net::URLRequestContextGetter> url_context_getter_;
+
+  scoped_ptr<net::URLFetcher> url_fetcher_;
+
+  const GURL wallpaper_url_;
+
+  const base::FilePath wallpaper_dir_;
+
+  const base::FilePath wallpaper_downloaded_file_;
+
+  const base::FilePath wallpaper_temporary_file_;
+
+  // Pending retry.
+  base::OneShotTimer<CustomizationWallpaperDownloader> request_scheduled_;
+
+  // Number of retry attempts.
+  unsigned retries_;
+
+  base::WeakPtrFactory<CustomizationWallpaperDownloader> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(CustomizationWallpaperDownloader);
+};
+
+}  //   namespace chromeos
+
+#endif  // CHROME_BROWSER_CHROMEOS_CUSTOMIZATION_WALLPAPER_DOWNLOADER_H_