cheets: add wallpaper observer to arc_wallpaper_service.

chrome/browser/chromeos/arc/arc_wallpaper_service.cc

 // Copyright 2016 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/arc/arc_wallpaper_service.h"
 
 #include <vector>
 
 #include "ash/common/wallpaper/wallpaper_controller.h"
 #include "ash/common/wm_shell.h"
@@ skipping 35 matching lines @@
 
   const AccountId& account_id =
       UserManager::Get()->GetPrimaryUser()->GetAccountId();
   wallpaper::WallpaperFilesId wallpaper_files_id =
       wallpaper_manager->GetFilesId(account_id);
   const bool update_wallpaper =
       account_id == UserManager::Get()->GetActiveUser()->GetAccountId();
   // TODO(crbug.com/618922): Allow specifying layout.
   wallpaper_manager->SetCustomWallpaper(
       account_id, wallpaper_files_id, kAndroidWallpaperFilename,
-      wallpaper::WALLPAPER_LAYOUT_STRETCH, user_manager::User::CUSTOMIZED,
-      image, update_wallpaper);
+      wallpaper::WALLPAPER_LAYOUT_CENTER_CROPPED,
+      user_manager::User::CUSTOMIZED, image, update_wallpaper);
 
   // TODO(crbug.com/618922): Register the wallpaper to Chrome OS wallpaper
   // picker. Currently the new wallpaper does not appear there. The best way to
   // make this happen seems to do the same things as wallpaper_api.cc and
   // wallpaper_private_api.cc.
 }
 
 std::vector<uint8_t> EncodeImagePng(const gfx::ImageSkia image) {
   std::vector<uint8_t> result;
   gfx::PNGCodec::FastEncodeBGRASkBitmap(*image.bitmap(), true, &result);
@@ skipping 75 matching lines @@
   DCHECK_CURRENTLY_ON(content::BrowserThread::UI);
   auto* wallpaper_instance =
       arc_bridge_service()->wallpaper()->GetInstanceForMethod(
           "OnWallpaperChanged", kMinOnWallpaperChangedVersion);
   if (!wallpaper_instance)
     return;
   wallpaper_instance->OnWallpaperChanged();
 }
 
 }  // namespace arc