[MD Bookmarks] Right click on bookmark items open context menu.

chrome/browser/resources/md_bookmarks/item.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-item',
 
   behaviors: [
     bookmarks.StoreClient,
   ],
@@ skipping 20 matching lines @@
     isFolder_: Boolean,
   },
 
   observers: [
     'updateFavicon_(item_.url)',
   ],
 
   listeners: {
     'click': 'onClick_',
     'dblclick': 'onDblClick_',
+    'contextmenu': 'onContextMenu_',
   },
 
   /** @override */
   attached: function() {
     this.watch('item_', function(store) {
       return store.nodes[this.itemId];
     }.bind(this));
     this.watch('isSelectedItem_', function(store) {
       return !!store.selection.items.has(this.itemId);
     }.bind(this));
 
     this.updateFromStore();
   },
 
   /** @return {BookmarksItemElement} */
   getDropTarget: function() {
     return this;
   },
 
   /**
    * @param {Event} e
    * @private
    */
+  onContextMenu_: function(e) {
+    e.preventDefault();

[tsergeant, 2017/04/13 01:15:47]

Minor suggestion: you should select the item here as well. It looks weird to
have one item selected, but then a different item with a context menu.

[calamity, 2017/04/13 04:56:46]

Done. This only happens if it's not selected since grouped selections should
stay where they are.

+    this.fire('open-item-menu', {
+      x: e.clientX,
+      y: e.clientY,
+      item: this.item_,
+    });
+  },
+
+  /**
+   * @param {Event} e
+   * @private
+   */
   onMenuButtonClick_: function(e) {
     e.stopPropagation();
     this.dispatch(bookmarks.actions.selectItem(
         this.itemId, false, false, this.getState()));
     this.fire('open-item-menu', {
-      target: e.target,
+      targetElement: e.target,
       item: this.item_,
     });
   },
 
   /**
    * @param {Event} e
    * @private
    */
   onMenuButtonDblClick_: function(e) {
     e.stopPropagation();
@@ skipping 34 matching lines @@
   },
 
   /**
    * @param {string} url
    * @private
    */
   updateFavicon_: function(url) {
     this.$.icon.style.backgroundImage = cr.icon.getFavicon(url);
   },
 });