history: add context menu buttons to the tab order.

chrome/browser/resources/history/other_devices.js

 // Copyright (c) 2013 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.
 
 /**
  * @fileoverview The section of the history page that shows tabs from sessions
                  on other devices.
  */
 
 ///////////////////////////////////////////////////////////////////////////////
@@ skipping 167 matching lines @@
 
   // Keep track of the drop down that triggered the menu, so we know
   // which element to apply the command to.
   var session = this.session_;
   function handleDropDownFocus(e) {
     DeviceContextMenuController.getInstance().setSession(session);
   }
   heading.addEventListener('contextmenu', handleDropDownFocus);
 
   var dropDownButton = new cr.ui.ContextMenuButton;
+  dropDownButton.tabIndex = 0;

[dmazzoni, 2014/10/10 05:31:18]

Should this be upstreamed to cr.ui.ContextMenuButton? When would you ever not
want it to be focusable?

   dropDownButton.classList.add('drop-down');
   dropDownButton.addEventListener('mousedown', function(event) {
       handleDropDownFocus(event);
       // Mousedown handling of cr.ui.MenuButton.handleEvent calls
       // preventDefault, which prevents blur of the focused element. We need to
       // do blur manually.
       document.activeElement.blur();
   });
   dropDownButton.addEventListener('focus', handleDropDownFocus);
   heading.appendChild(dropDownButton);
@@ skipping 332 matching lines @@
 
   var doSearch = function(e) {
     devicesView.setSearchText($('search-field').value);
   };
   $('search-field').addEventListener('search', doSearch);
   $('search-button').addEventListener('click', doSearch);
 }
 
 // Add handlers to HTML elements.
 document.addEventListener('DOMContentLoaded', load);