[MD Bookmarks] Restore focus after closing a dialog or context menu.

chrome/browser/resources/md_bookmarks/edit_dialog.js

 // Copyright 2017 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-edit-dialog',
 
   properties: {
     /** @private */
     isFolder_: Boolean,
@@ skipping 25 matching lines @@
    * inserted into the tree as a child of |parentId|.
    * @param {boolean} isFolder
    * @param {string} parentId
    */
   showAddDialog: function(isFolder, parentId) {
     this.reset_();
     this.isEdit_ = false;
     this.isFolder_ = isFolder;
     this.parentId_ = parentId;
 
-    this.$.dialog.showModal();
+    bookmarks.DialogFocusManager.getInstance().showDialog(this.$.dialog);
   },
 
   /**
    * Show the edit dialog for |editItem|.
    * @param {BookmarkNode} editItem
    */
   showEditDialog: function(editItem) {
     this.reset_();
     this.isEdit_ = true;
     this.isFolder_ = !editItem.url;
     this.editItem_ = editItem;
 
     this.titleValue_ = editItem.title;
     if (!this.isFolder_)
       this.urlValue_ = assert(editItem.url);
 
-    this.$.dialog.showModal();
+    bookmarks.DialogFocusManager.getInstance().showDialog(this.$.dialog);
   },
 
   /**
    * Clear out existing values from the dialog, allowing it to be reused.
    * @private
    */
   reset_: function() {
     this.editItem_ = null;
     this.parentId_ = null;
     this.$.url.invalid = false;
@@ skipping 56 matching lines @@
       chrome.bookmarks.create(edit);
     }
     this.$.dialog.close();
   },
 
   /** @private */
   onCancelButtonTap_: function() {
     this.$.dialog.cancel();
   },
 });