Fix accessibility in Windows x64 build.

ui/views/win/hwnd_message_handler.cc

 // 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.
 
 #include "ui/views/win/hwnd_message_handler.h"
 
 #include <dwmapi.h>
 #include <oleacc.h>
 #include <shellapi.h>
 #include <wtsapi32.h>
@@ skipping 1397 matching lines @@
     minmax_info->ptMaxTrackSize.x = max_window_size.width();
     minmax_info->ptMaxTrackSize.y = max_window_size.height();
   }
   SetMsgHandled(FALSE);
 }
 
 LRESULT HWNDMessageHandler::OnGetObject(UINT message,
                                         WPARAM w_param,
                                         LPARAM l_param) {
   LRESULT reference_result = static_cast<LRESULT>(0L);
+  // Explicitly cast to DWORD for 64-bit support.
+  DWORD obj_id = static_cast<DWORD>(l_param);

[jschuh, 2014/06/13 23:49:27]

Sorry to be pedantic, but this is an undefined conversion, so it would blow up
on e.g. lexan. You should actually just leave l_param as it is and expand
OBJID_CLIENT as follows:

static const LPARAM kObjIdClient = static_cast<ULONG>(OBJID_CLIENT);

[dmazzoni, 2014/06/15 07:56:03]

OK.

 
   // Accessibility readers will send an OBJID_CLIENT message
-  if (OBJID_CLIENT == l_param) {
+  if (OBJID_CLIENT == obj_id) {

[jschuh, 2014/06/13 23:49:27]

This would become:

if (kObjIdClient == obj_id) {

[dmazzoni, 2014/06/15 07:56:03]

Done.

     // Retrieve MSAA dispatch object for the root view.
     base::win::ScopedComPtr<IAccessible> root(
         delegate_->GetNativeViewAccessible());
 
     // Create a reference that MSAA will marshall to the client.
     reference_result = LresultFromObject(IID_IAccessible, w_param,
         static_cast<IAccessible*>(root.Detach()));
   }
 
   return reference_result;
@@ skipping 989 matching lines @@
     POINT cursor_pos = {0};
     ::GetCursorPos(&cursor_pos);
     if (memcmp(&cursor_pos, &mouse_location, sizeof(POINT)))
       return false;
     return true;
   }
   return false;
 }
 
 }  // namespace views