[MD Bookmarks] Scroll selected folder into view in sidebar.

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.StoreClient,
   ],
@@ skipping 43 matching lines @@
       return state.closedFolders.has(this.itemId);
     }.bind(this));
     this.watch('selectedFolder_', function(state) {
       return state.selectedFolder;
     });
     this.watch('searchActive_', function(state) {
       return bookmarks.util.isShowingSearch(state);
     });
 
     this.updateFromStore();
+
+    if (this.isSelectedFolder_) {
+      this.async(function() {
+        this.scrollIntoViewIfNeeded();
+      });
+    }
   },
 
   /** @return {HTMLElement} */
   getFocusTarget: function() {
     return this.$.container;
   },
 
   /** @return {HTMLElement} */
   getDropTarget: function() {
     return this.$.container;
@@ skipping 218 matching lines @@
   },
 
   /**
    * @private
    * @return {string}
    */
   getTabIndex_: function() {
     return this.isSelectedFolder_ ? '0' : '';
   },
 });