Remove the old wallpaper picker code

chrome/browser/resources/options/chromeos/set_wallpaper_options.css

-/* 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. */
-
-#wallpaper-title > span {
-  -webkit-padding-start: 17px;
-  padding-top: 6px;
-}
-
-#set-wallpaper-page .content-area {
-  height: 400px;
-}
-
-#wallpaper-grid {
-  margin: 0;
-  overflow: hidden;
-  width: 580px;
-}
-
-#wallpaper-grid img {
-  height: 80px;
-  width: 128px;
-}
-
-.grayout img {
-  -webkit-filter: opacity(50%);
-}
-
-.bottom-bar {
-  -webkit-box-orient: vertical;
-  display: -webkit-box;
-}
-
-.bottom-bar .spacer {
-  -webkit-box-flex: 1;
-}
-
-.wallpaper-image-attr {
-  -webkit-padding-start: 34px;
-  line-height: 26px;
-  padding-top: 14px;
-}
-
-#wallpaper-author-website {
-  -webkit-padding-start: 5px;
-}
-
-#wallpaper-action-area {
-  -webkit-padding-start: 34px;
-  padding-top: 0;
-}