win32: Add a PlatformWindow implementation for Windows.

ui/platform_window/win/win_window.gyp

Index: ui/platform_window/win/win_window.gyp
diff --git a/ui/platform_window/x11/x11_window.gyp b/ui/platform_window/win/win_window.gyp
similarity index 58%
copy from ui/platform_window/x11/x11_window.gyp
copy to ui/platform_window/win/win_window.gyp
index efb86c8d1d2edf1d886dfe16c82959022267386f..e6d866426e26888f4bc56bb538979f9039f08ba2 100644
--- a/ui/platform_window/x11/x11_window.gyp
+++ b/ui/platform_window/win/win_window.gyp
@@ -5,25 +5,23 @@
 {
   'variables': {
     'chromium_code': 1,
-    'use_x11': 1,
   },
   'targets': [{
-    'target_name': 'x11_window',
+    'target_name': 'win_window',
     'type': '<(component)',
     'dependencies': [
       '../../../base/base.gyp:base',
-      '../../../build/linux/system.gyp:x11',
       '../../../skia/skia.gyp:skia',
       '../../events/events.gyp:events',
-      '../../events/platform/x11/x11_events_platform.gyp:x11_events_platform',
-      '../../gfx/x/gfx_x11.gyp:gfx_x11',
+      '../../gfx/gfx.gyp:gfx',
+      '../../gfx/gfx.gyp:gfx_geometry',
       '../platform_window.gyp:platform_window',
     ],
-    'defines': [ 'X11_WINDOW_IMPLEMENTATION' ],
+    'defines': [ 'WIN_WINDOW_IMPLEMENTATION' ],
     'sources': [
-      'x11_window.cc',
-      'x11_window.h',
-      'x11_window_export.h',
+      'win_window.cc',
+      'win_window.h',
+      'win_window_export.h',
     ],
   }],
 }