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

chrome/browser/chromeos/login/user_manager.cc

Index: chrome/browser/chromeos/login/user_manager.cc
diff --git a/chrome/browser/chromeos/login/user_manager.cc b/chrome/browser/chromeos/login/user_manager.cc
index 3b56995820865b357fa56d6669ff451387731f35..6071c003838a8ad59f4125d7a3d333091a21ef5d 100644
--- a/chrome/browser/chromeos/login/user_manager.cc
+++ b/chrome/browser/chromeos/login/user_manager.cc
@@ -839,6 +839,22 @@ void UserManager::SetInitialUserImage(const std::string& username) {
   SaveUserDefaultImageIndex(username, image_id);
 }
 
+int UserManager::GetUserWallpaper(const std::string& username) {
+  User* user = const_cast<User*>(FindUser(username));
+  if (user) {
+    return user->wallpaper_index();
+  }
+  return User::kDefaultWallpaperIndex;
+}
+
+void UserManager::SetUserWallpaper(const std::string& username,
+                                   int wallpaper_index) {
+  User* user = const_cast<User*>(FindUser(username));
+  if (user) {
+    user->SetWallpaper(wallpaper_index);
+  }
+}
+
 void UserManager::SetUserImage(const std::string& username,
                                int image_index,
                                const SkBitmap& image) {