[MD Bookmarks] Add import/export bookmarks HTML features

chrome/browser/resources/md_bookmarks/toolbar.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-toolbar',
 
   properties: {
     searchTerm: {
       type: String,
@@ skipping 25 matching lines @@
   onSortTap_: function() {
     this.closeDropdownMenu_();
   },
 
   /** @private */
   onAddBookmarkTap_: function() {
     this.closeDropdownMenu_();
   },
 
   /** @private */
-  onAddImportTap_: function() {
+  onImportTap_: function() {
+    chrome.bookmarks.import();
     this.closeDropdownMenu_();
   },
 
   /** @private */
-  onAddExportTap_: function() {
+  onExportTap_: function() {
+    chrome.bookmarks.export();
     this.closeDropdownMenu_();
   },
 
   /** @private */
   closeDropdownMenu_: function() {
     var menu = /** @type {!CrActionMenuElement} */ (this.$.dropdown);
     menu.close();
   },
 
   /**
    * @param {Event} e
    * @private
    */
   onSearchChanged_: function(e) {
     var searchTerm = /** @type {string} */ (e.detail);
     this.fire('search-term-changed', searchTerm);
   },
 
   /** @private */
   onSearchTermChanged_: function() {
     this.searchField.setValue(this.searchTerm || '');
   },
 });