Adds a class that makes it easy to subclass a HWND and filter messages sent to it.

ui/ui.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,
   },
   'includes': [
     'ui_resources.gypi',
@@ skipping 239 matching lines @@
         'base/view_prop.cc',
         'base/view_prop.h',
         'base/win/atl_module.h',
         'base/win/dpi.cc',
         'base/win/dpi.h',
         'base/win/events_win.cc',
         'base/win/foreground_helper.cc',
         'base/win/foreground_helper.h',
         'base/win/hwnd_util.cc',
         'base/win/hwnd_util.h',
+        'base/win/hwnd_subclass.cc',
+        'base/win/hwnd_subclass.h',
         'base/win/ime_input.cc',
         'base/win/ime_input.h',
         'base/win/message_box_win.cc',
         'base/win/message_box_win.h',
         'base/win/mouse_wheel_util.cc',
         'base/win/mouse_wheel_util.h',
         'base/win/scoped_ole_initializer.cc',
         'base/win/scoped_ole_initializer.h',
         'base/win/scoped_set_map_mode.h',
         'base/win/shell.cc',
@@ skipping 472 matching lines @@
                 'shutil.copyfile(\'<(ui_copy_target)\', \'<(ui_copy_dest)\'); ' \
                 'os.chmod(\'<(ui_copy_dest)\', 0700)'
               ]
             }
           ],
         },
       ],
     }],
   ],
 }