Views: factor out Combobox background and const-ify style

ui/views/examples/examples.gyp

 # Copyright 2014 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,
   },
   'targets': [
     {
       # GN version: //ui/views/examples
@@ skipping 144 matching lines @@
         'views_examples_with_content_export.h',
         'webview_example.cc',
         'webview_example.h',
       ],
     },  # target_name: views_examples_with_content_lib
     {
       # GN version: //ui/views/examples/views_examples_with_content_exe
       'target_name': 'views_examples_with_content_exe',
       'type': 'executable',
       'dependencies': [
+        '../resources/views_resources.gyp:views_resources',
         '../../views_content_client/views_content_client.gyp:views_content_client',
         'views_examples_with_content_lib',
       ],
       'sources': [
         # Note: sources list duplicated in GN build.
         'examples_with_content_main_exe.cc',
       ],
       'conditions': [
         ['component=="shared_library"', {
           'dependencies': [
@@ skipping 20 matching lines @@
           },
           'dependencies': [
             '../../../sandbox/sandbox.gyp:sandbox',
             '../../../content/content.gyp:sandbox_helper_win',
           ],
         }],
       ],
     },  # target_name: views_examples_with_content_exe
   ],
 }