Add the button style for combobox

ui/views/views.gyp

 # 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.
 {
   'variables': {
     'chromium_code': 1,
   },
   'target_defaults': {
     'conditions': [
       ['use_aura==1', {
@@ skipping 78 matching lines @@
         'controls/button/menu_button.cc',
         'controls/button/menu_button.h',
         'controls/button/menu_button_listener.h',
         'controls/button/radio_button.cc',
         'controls/button/radio_button.h',
         'controls/button/text_button.cc',
         'controls/button/text_button.h',
         'controls/combobox/combobox.cc',
         'controls/combobox/combobox.h',
         'controls/combobox/combobox_listener.h',
+        'controls/combobox/combobox_menu_runner.h',
         'controls/focusable_border.cc',
         'controls/focusable_border.h',
         'controls/glow_hover_controller.cc',
         'controls/glow_hover_controller.h',
         'controls/image_view.cc',
         'controls/image_view.h',
         'controls/label.cc',
         'controls/label.h',
         'controls/link.cc',
         'controls/link.h',
@@ skipping 990 matching lines @@
           'sources/': [
             # This is needed because the aura rule strips it from the default
             # sources list.
             ['include', '^../../content/app/startup_helper_win.cc'],
           ],
         }],
       ],
     },  # target_name: views_examples_with_content_exe
   ],
 }