MD Bookmarks: Focus sidebar nodes on click without showing an outline

chrome/browser/resources/md_bookmarks/folder_node.js

 // Copyright 2016 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.
 
 Polymer({
   is: 'bookmarks-folder-node',
 
   behaviors: [
+    bookmarks.MouseFocusBehavior,
     bookmarks.StoreClient,
   ],
 
   properties: {
     itemId: {
       type: String,
       observer: 'updateFromStore',
     },
 
     depth: {
@@ skipping 43 matching lines @@
 
     this.updateFromStore();
 
     if (this.isSelectedFolder_) {
       this.async(function() {
         this.scrollIntoViewIfNeeded();
       });
     }
   },
 
-  /** @return {HTMLElement} */
+  /**
+   * Overriden from bookmarks.MouseFocusBehavior.
+   * @return {!HTMLElement}
+   */
   getFocusTarget: function() {
     return this.$.container;
   },
 
   /** @return {HTMLElement} */
   getDropTarget: function() {
     return this.$.container;
   },
 
   /** @return {boolean} */
@@ skipping 254 matching lines @@
    */
   isRootFolder_: function() {
     return this.itemId == ROOT_NODE_ID;
   },
 
   /**
    * @private
    * @return {string}
    */
   getTabIndex_: function() {
-    return this.isSelectedFolder_ ? '0' : '';
+    return this.isSelectedFolder_ ? '0' : '-1';
   },
 });