Enable user change background image in settings page in Aura build.

chrome/browser/chromeos/login/user_manager.h

Index: chrome/browser/chromeos/login/user_manager.h
diff --git a/chrome/browser/chromeos/login/user_manager.h b/chrome/browser/chromeos/login/user_manager.h
index 6e70d7cccc4a2a00169a9fe6400573e316668955..6624dfb9da26b92def03a2ee322193eb77b23fdc 100644
--- a/chrome/browser/chromeos/login/user_manager.h
+++ b/chrome/browser/chromeos/login/user_manager.h
@@ -99,6 +99,10 @@ class UserManager : public ProfileDownloaderDelegate,
   // Otherwise, returns |username| itself.
   std::string GetUserDisplayEmail(const std::string& username) const;
 
+  int GetUserWallpaper(const std::string& username);
+  void SetUserWallpaper(const std::string& username,
+                        int wallpaper_index);
+
   // Sets user image to the default image with index |image_index|, sends
   // LOGIN_USER_IMAGE_CHANGED notification and updates Local State.
   void SaveUserDefaultImageIndex(const std::string& username, int image_index);