Add ui::GrabDesktopSnapshot for Windows.

ui/snapshot/snapshot.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,
   },
   'targets': [
     {
@@ skipping 20 matching lines @@
       'include_dirs': [
         '..',
       ],
       'conditions': [
         ['use_aura==1', {
           'dependencies': [
             '../aura/aura.gyp:aura',
             '../compositor/compositor.gyp:compositor',
           ],
         }],
-        ['use_aura==1 and OS=="win"', {
-          'sources/': [
-            ['exclude', 'snapshot_win.cc'],
-          ],
-        }],
       ],
     },
     {
       'target_name': 'snapshot_unittests',
       'type': '<(gtest_target_type)',
       'dependencies': [
         '../../skia/skia.gyp:skia',
         '../../base/base.gyp:base',
         '../../testing/gtest.gyp:gtest',
         '../../testing/gmock.gyp:gmock',
         '../../testing/gtest.gyp:gtest',
         '../ui.gyp:ui',
         'snapshot'
       ],
       'sources': [
         'snapshot_mac_unittest.mm',
       ]
     },
   ],
 }