components: Create web_modal component.

components/components.gyp

 # 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.
 
 {
   'variables': {
     # This turns on e.g. the filename-based detection of which
     # platforms to include source files on (e.g. files ending in
     # _mac.h or _mac.cc are only compiled on MacOSX).
     'chromium_code': 1,
    },
   'includes': [
     'autofill.gypi',
     'auto_login_parser.gypi',
     'components_tests.gypi',
     'navigation_interception.gypi',
     'sessions.gypi',
     'user_prefs.gypi',
     'visitedlink.gypi',
     'webdata.gypi',
     'web_contents_delegate_android.gypi',
+    'web_modal.gypi',
   ],
 }