clang/win: Let some chromium_code targets build with -Wextra.

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>
 
@@ skipping 1395 matching lines @@
 LRESULT HWNDMessageHandler::OnGetObject(UINT message,
                                         WPARAM w_param,
                                         LPARAM l_param) {
   LRESULT reference_result = static_cast<LRESULT>(0L);
 
   // Only the lower 32 bits of l_param are valid when checking the object id
   // because it sometimes gets sign-extended incorrectly (but not always).
   DWORD obj_id = static_cast<DWORD>(static_cast<DWORD_PTR>(l_param));
 
   // Accessibility readers will send an OBJID_CLIENT message
-  if (OBJID_CLIENT == obj_id) {
+  if (static_cast<DWORD>(OBJID_CLIENT) == obj_id) {
     // 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 1050 matching lines @@
       ui::INPUT_EVENT_LATENCY_ORIGINAL_COMPONENT,
       0,
       0,
       event_time,
       1);
 
   touch_events->push_back(event);
 }
 
 }  // namespace views