Swallow double-click events on menu buttons in Web UI in chrome://bookmarks.

ui/webui/resources/js/cr/ui/menu_button.js

 // Copyright (c) 2012 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.
 
 // <include src="../../assert.js">
 
 cr.exportPath('cr.ui');
 
 /**
  * Enum for type of hide. Delayed is used when called by clicking on a
@@ skipping 26 matching lines @@
 
   MenuButton.prototype = {
     __proto__: HTMLButtonElement.prototype,
 
     /**
      * Initializes the menu button.
      */
     decorate: function() {
       this.addEventListener('mousedown', this);
       this.addEventListener('keydown', this);
+      this.addEventListener('dblclick', this);
 
       // Adding the 'custom-appearance' class prevents widgets.css from changing
       // the appearance of this element.
       this.classList.add('custom-appearance');
       this.classList.add('menu-button');  // For styles in menu_button.css.
 
       var menu;
       if ((menu = this.getAttribute('menu')))
         this.menu = menu;
 
@@ skipping 98 matching lines @@
           this.hideMenu();
           break;
         case 'contextmenu':
           if ((!this.menu || !this.menu.contains(e.target)) &&
               (!this.hideTimestamp_ || Date.now() - this.hideTimestamp_ > 50))
             this.showMenu(true);
           e.preventDefault();
           // Don't allow elements further up in the DOM to show their menus.
           e.stopPropagation();
           break;
+        case 'dblclick':
+          // Don't allow double click events to propagate.
+          e.preventDefault();
+          e.stopPropagation();
+          break;
       }
     },
 
     /**
      * Shows the menu.
      * @param {boolean} shouldSetFocus Whether to set focus on the
      *     selected menu item.
      */
     showMenu: function(shouldSetFocus) {
       this.hideMenu();
@@ skipping 138 matching lines @@
         'drop-down-arrow-hover', ARROW_WIDTH, ARROW_HEIGHT, opt_hoverColor);
     createDropDownArrowCanvas(
         'drop-down-arrow-active', ARROW_WIDTH, ARROW_HEIGHT, opt_activeColor);
   };
 
   // Export
   return {
     MenuButton: MenuButton,
   };
 });