This CL replaces e-mail with AccountId in wallpaper manager code.

chrome/browser/chromeos/extensions/wallpaper_api.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_CHROMEOS_EXTENSIONS_WALLPAPER_API_H_
 #define CHROME_BROWSER_CHROMEOS_EXTENSIONS_WALLPAPER_API_H_
 
 #include "base/threading/sequenced_worker_pool.h"
 #include "chrome/browser/chromeos/extensions/wallpaper_function_base.h"
 #include "chrome/common/extensions/api/wallpaper.h"
+#include "components/signin/core/account_id/account_id.h"
 #include "net/url_request/url_request_status.h"
 
 // Implementation of chrome.wallpaper.setWallpaper API.
 // After this API being called, a jpeg encoded wallpaper will be saved to
 // /home/chronos/custom_wallpaper/{resolution}/{user_id_hash}/file_name. The
 // wallpaper can then persistent after Chrome restart. New call to this API
 // will replace the previous saved wallpaper with new one.
 // Note: For security reason, the original encoded wallpaper image is not saved
 // directly. It is decoded and re-encoded to jpeg format before saved to file
 // system.
@@ skipping 23 matching lines @@
 
   // Called by OnURLFetchComplete().
   void OnWallpaperFetched(bool success, const std::string& response);
 
   scoped_ptr<extensions::api::wallpaper::SetWallpaper::Params> params_;
 
   // Unique file name of the custom wallpaper.
   std::string file_name_;
 
   // User id of the user who initiate this API call.
-  std::string user_id_;
+  AccountId account_id_ = EmptyAccountId();
 
   // User id hash of the logged in user.
   std::string user_id_hash_;
 
   // Sequence token associated with wallpaper operations. Shared with
   // WallpaperManager.
   base::SequencedWorkerPool::SequenceToken sequence_token_;
 };
 
 #endif  // CHROME_BROWSER_CHROMEOS_EXTENSIONS_WALLPAPER_API_H_