Use chrome_html structure for shared_resources and options2 page.

chrome/browser/resources/options2/browser_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. */
 
 #change-home-page-section {
   margin-left: 30px;
 }
 
 #home-page-url {
   display: inline-block;
@@ skipping 167 matching lines @@
   75%  {
     background-position: 0 50%;
   }
   87.5%  {
     background-position: 0 25%;
   }
 }
 
 .network-wifi {
   background-image: url('chrome://theme/IDR_STATUSBAR_NETWORK_ARCS_DARK');
+  background-size: 25px;
 }
 
 .network-wimax {
   background-image: url('chrome://theme/IDR_STATUSBAR_NETWORK_BARS_DARK');
+  background-size: 25px;
 }
 
 .network-cellular {
   background-image: url('chrome://theme/IDR_STATUSBAR_NETWORK_BARS_DARK');
+  background-size: 25px;
 }
 
 .network-vpn {
   background-image: url('chrome://theme/IDR_STATUSBAR_VPN');
+  background-size: 25px;
 }
 
 .network-add-connection,
 .network-control-active,
 .network-control-inactive {
   background-position: center center !important;
   background-repeat: no-repeat;
 }
 
 .network-add-connection {
   background-image: url('chrome://theme/IDR_SIDETABS_NEW_TAB');
+  background-size: 16px;
 }
 
 .network-control-inactive {
   background-image: none;
 }
 
 .network-control-active {
   background-image: url('chrome://theme/IDR_PROFILE_SELECTED');
+  background-size: 16px;
 }
 
 .network-options-button {
   -webkit-box-flex: 0;
   -webkit-transform: scale(0.6);
   background-image: none;
   background-position: center center;
   display: block;
   opacity: 0.5;
   vertical-align: middle;
   width: 19px;
 }
 
 .network-menu-item:hover .network-options-button {
   background-image: url('chrome://theme/IDR_STATUSBAR_EDIT');
+  background-size: 25px;
 }
 
 .network-group > .controlled-setting-indicator,
 .network-menu-item > .controlled-setting-indicator {
   -webkit-box-flex: 0;
   -webkit-margin-end: 5px;
   display: block;
   height: 16px;
   margin-top: 9px;
   width: 16px;
@@ skipping 159 matching lines @@
 }
 
 .sliding {
   -webkit-transition: height 200ms;
   overflow-y: hidden;
 }
 
 #sessionRestoreOverlay {
   width: 500px;
 }