Reverting 27113.

base/win_util.cc

 // Copyright (c) 2006-2008 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.
 
 #include "base/win_util.h"
 
 #include <sddl.h>
 
 #include "base/logging.h"
 #include "base/registry.h"
@@ skipping 261 matching lines @@
 bool IsSubclassed(HWND window, WNDPROC subclass_proc) {
   WNDPROC original_handler =
       reinterpret_cast<WNDPROC>(GetWindowLongPtr(window, GWLP_WNDPROC));
   return original_handler == subclass_proc;
 }
 
 bool Subclass(HWND window, WNDPROC subclass_proc) {
   WNDPROC original_handler =
       reinterpret_cast<WNDPROC>(GetWindowLongPtr(window, GWLP_WNDPROC));
   if (original_handler != subclass_proc) {
-    DCHECK(!GetProp(window, kHandlerKey)) << "subclassing a HWND more than "
-        "once";
     win_util::SetWindowProc(window, subclass_proc);
     SetProp(window, kHandlerKey, original_handler);
     return true;
   }
   return false;
 }
 
 bool Unsubclass(HWND window, WNDPROC subclass_proc) {
   WNDPROC current_handler =
       reinterpret_cast<WNDPROC>(GetWindowLongPtr(window, GWLP_WNDPROC));
@@ skipping 97 matching lines @@
 
 #ifndef COPY_FILE_COPY_SYMLINK
 #error You must install the Windows 2008 or Vista Software Development Kit and \
 set it as your default include path to build this library. You can grab it by \
 searching for "download windows sdk 2008" in your favorite web search engine.  \
 Also make sure you register the SDK with Visual Studio, by selecting \
 "Integrate Windows SDK with Visual Studio 2005" from the Windows SDK \
 menu (see Start - All Programs - Microsoft Windows SDK - \
 Visual Studio Registration).
 #endif