If customization includes default wallpaper, download and apply it.

chrome/browser/chromeos/extensions/wallpaper_private_api.cc

 // Copyright (c) 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.
 
 #include "chrome/browser/chromeos/extensions/wallpaper_private_api.h"
 
 #include <vector>
 
 #include "ash/ash_switches.h"
 #include "ash/desktop_background/desktop_background_controller.h"
@@ skipping 427 matching lines @@
         file_name).InsertBeforeExtension(chromeos::kSmallWallpaperSuffix);
     if (base::PathExists(file_path))
       return;
     // Generates and saves small resolution wallpaper. Uses CENTER_CROPPED to
     // maintain the aspect ratio after resize.
     chromeos::WallpaperManager::Get()->ResizeAndSaveWallpaper(
         wallpaper,
         file_path,
         ash::WALLPAPER_LAYOUT_CENTER_CROPPED,
         ash::kSmallWallpaperMaxWidth,
-        ash::kSmallWallpaperMaxHeight);
+        ash::kSmallWallpaperMaxHeight,
+        NULL);
   } else {
     std::string error = base::StringPrintf(
         "Failed to create/write wallpaper to %s.", file_name.c_str());
     BrowserThread::PostTask(
         BrowserThread::UI, FROM_HERE,
         base::Bind(&WallpaperPrivateSetWallpaperFunction::OnFailure,
                    this, error));
   }
 }
 
@@ skipping 122 matching lines @@
   chromeos::UserImage wallpaper(*image.get());
   if (!base::PathExists(thumbnail_path.DirName()))
     base::CreateDirectory(thumbnail_path.DirName());
 
   scoped_refptr<base::RefCountedBytes> data;
   chromeos::WallpaperManager::Get()->ResizeWallpaper(
       wallpaper,
       ash::WALLPAPER_LAYOUT_STRETCH,
       ash::kWallpaperThumbnailWidth,
       ash::kWallpaperThumbnailHeight,
-      &data);
+      &data,
+      NULL);
   BrowserThread::PostTask(
         BrowserThread::UI, FROM_HERE,
         base::Bind(
             &WallpaperPrivateSetCustomWallpaperFunction::ThumbnailGenerated,
             this, data));
 }
 
 void WallpaperPrivateSetCustomWallpaperFunction::ThumbnailGenerated(
     base::RefCountedBytes* data) {
   BinaryValue* result = BinaryValue::CreateWithCopiedBuffer(
@@ skipping 247 matching lines @@
                  this, file_list));
 }
 
 void WallpaperPrivateGetOfflineWallpaperListFunction::OnComplete(
     const std::vector<std::string>& file_list) {
   base::ListValue* results = new base::ListValue();
   results->AppendStrings(file_list);
   SetResult(results);
   SendResponse(true);
 }