Speed up custom wallpaper switching time and wallpaper manager code refactor

chrome/browser/chromeos/login/user.cc

 // Copyright (c) 2012 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/login/user.h"
 
 #include "base/stringprintf.h"
 #include "base/utf_string_conversions.h"
 #include "chrome/browser/chromeos/login/default_user_images.h"
 #include "chrome/browser/chromeos/login/user_manager.h"
@@ skipping 49 matching lines @@
   user_image_.set_url(image_url);
 }
 
 void User::SetStubImage(int image_index) {
   user_image_.SetImage(*ResourceBundle::GetSharedInstance().GetImageSkiaNamed(
       kStubImageResourceID));
   image_index_ = image_index;
   image_is_stub_ = true;
 }
 
-void User::SetWallpaperThumbnail(const SkBitmap& wallpaper_thumbnail) {
-  wallpaper_thumbnail_ = wallpaper_thumbnail;
-}
-
 std::string User::GetAccountName(bool use_display_email) const {
   if (use_display_email && !display_email_.empty())
     return GetUserName(display_email_);
   else
     return GetUserName(email_);
 }
 
 string16 User::GetDisplayName() const {
   // Fallback to the email account name in case display name haven't been set.
   return display_name_.empty() ?
       UTF8ToUTF16(GetAccountName(true)) :
       display_name_;
 }
 
 }  // namespace chromeos