MD History: Add confirmation dialog when deleting items from the toolbar

chrome/browser/resources/md_history/history_list.js

 // Copyright 2015 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: 'history-list',
 
   properties: {
     // The search term for the current query. Set when the query returns.
     searchedTerm: {
@@ skipping 163 matching lines @@
         this.historyData_.splice(i, 1);
       }
     }
     // notifySplices gives better performance than individually splicing as it
     // batches all of the updates together.
     this.notifySplices('historyData_', splices);
   },
 
   /**
    * Performs a request to the backend to delete all selected items. If
-   * successful, removes them from the view.
+   * successful, removes them from the view. Does not prompt the user before
+   * deleting -- see <history-list-container> for a version of this method which
+   * does prompt.
    */
   deleteSelected: function() {
     var toBeRemoved = this.historyData_.filter(function(item) {
       return item.selected;
     });
     md_history.BrowserService.getInstance()
         .deleteItems(toBeRemoved)
         .then(function(items) {
           this.removeDeletedHistory_(items);
           this.fire('unselect-all');
@@ skipping 70 matching lines @@
 
   /**
    * @param {number} index
    * @return {boolean}
    * @private
    */
   isFirstItem_: function(index) {
     return index == 0;
   }
 });