Add support for favicon scale factor in WebUI

chrome/browser/resources/options/search_engine_manager_engine_list.js

 // 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.
 
 cr.define('options.search_engines', function() {
   /** @const */ var InlineEditableItemList = options.InlineEditableItemList;
   /** @const */ var InlineEditableItem = options.InlineEditableItem;
   /** @const */ var ListSelectionController = cr.ui.ListSelectionController;
 
   /**
@@ skipping 78 matching lines @@
 
       // Construct the name column.
       var nameColEl = this.ownerDocument.createElement('div');
       nameColEl.className = 'name-column';
       nameColEl.classList.add('weakrtl');
       this.contentElement.appendChild(nameColEl);
 
       // Add the favicon.
       var faviconDivEl = this.ownerDocument.createElement('div');
       faviconDivEl.className = 'favicon';
-      var imgEl = this.ownerDocument.createElement('img');
-      imgEl.src = 'chrome://favicon/iconurl/' + engine.iconURL;
-      faviconDivEl.appendChild(imgEl);
+      if (!this.isPlaceholder) {
+        faviconDivEl.style.backgroundImage =
+            url('chrome://favicon/iconurl@' + window.devicePixelRatio + 'x/' +
+                engine.iconURL);
+      }
       nameColEl.appendChild(faviconDivEl);
 
       var nameEl = this.createEditableTextCell(engine.displayName);
       nameEl.classList.add('weakrtl');
       nameColEl.appendChild(nameEl);
 
       // Then the keyword column.
       var keywordEl = this.createEditableTextCell(engine.keyword);
       keywordEl.className = 'keyword-column';
       keywordEl.classList.add('weakrtl');
@@ skipping 194 matching lines @@
     },
   };
 
   // Export
   return {
     SearchEngineList: SearchEngineList
   };
 
 });