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': [
     {
       'target_name': 'snapshot',
       'type': '<(component)',
       'dependencies': [
         '../../skia/skia.gyp:skia',
         '../../base/base.gyp:base',
         '../ui.gyp:ui',
       ],
       'defines': [
         'SNAPSHOT_IMPLEMENTATION',
       ],
       'sources': [
         'snapshot.h',
         'snapshot_android.cc',
         'snapshot_aura.cc',
         'snapshot_export.h',
         'snapshot_gtk.cc',
+        'snapshot_hwnd_win.cc',

[sky, 2013/04/22 16:25:19]

Why is this file both here and in test support?

[grt (UTC plus 2), 2013/04/22 19:14:03]

The desktop snapshotting code (in 'snapshot_test_support' target) is identical
to the non-Aura window snapshotting code (in 'snapshot' target). To avoid source
code duplication, I pulled this implementation out of snapshot_win and into
snapshot_hwnd_win, and include it in both targets. It is omitted from 'snapshot'
for Aura builds, but is unconditionally present in 'snapshot_test_support' so
that desktop snapshotting can be done from tests. I experimented with having it
appear in only one or the other (and never both), but found that the gyp hijinks
to make that work was too confusing. I've moved desktop_snapshot.{cc,h} into a
test/ subdir to make it more explicit that these are test-only files.

+        'snapshot_hwnd_win.h',
         'snapshot_ios.mm',
         'snapshot_mac.mm',
         'snapshot_win.cc',
       ],
       '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'],
+          'sources!': [
+            'snapshot_hwnd_win.cc',
+            'snapshot_hwnd_win.h',
+            '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',
       ]
     },
   ],
+  'conditions': [
+    ['OS=="win"', {
+      'targets': [
+        {
+          'target_name': 'snapshot_test_support',
+          'type': 'static_library',
+          'sources': [
+            'snapshot_desktop.h',
+            'snapshot_desktop_win.cc',
+            'snapshot_hwnd_win.cc',
+            'snapshot_hwnd_win.h',
+          ],
+          'dependencies': [
+            '../../base/base.gyp:base',
+            '../../skia/skia.gyp:skia',
+            '../ui.gyp:ui',
+          ],
+        },
+      ],
+    }, {  # else (OS!="win")
+      'targets': [
+        {
+          'target_name': 'snapshot_test_support',
+          'type': 'none',
+          'sources': [],
+        },
+      ],
+    }],
+  ],
 }