Fix a crasher with "select file" dialogs.

app/win/window_impl.cc

 // Copyright (c) 2009 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 "app/win/window_impl.h"
 
 #include <list>
 
 #include "base/singleton.h"
 #include "base/string_util.h"
@@ skipping 134 matching lines @@
   DCHECK(hwnd_);
 
   // The window procedure should have set the data for us.
   DCHECK(win_util::GetWindowUserData(hwnd_) == this);
 }
 
 HICON WindowImpl::GetDefaultWindowIcon() const {
   return NULL;
 }
 
+// static
+bool WindowImpl::IsWindowImpl(HWND hwnd) {
+  wchar_t tmp[128];
+  if (!::GetClassName(hwnd, tmp, 128))
+    return false;
+
+  std::wstring class_name(tmp);
+  return class_name.find(kBaseClassName) == 0;
+}
+
 LRESULT WindowImpl::OnWndProc(UINT message, WPARAM w_param, LPARAM l_param) {
   LRESULT result = 0;
 
   // Handle the message if it's in our message map; otherwise, let the system
   // handle it.
   if (!ProcessWindowMessage(hwnd_, message, w_param, l_param, result))
     result = DefWindowProc(hwnd_, message, w_param, l_param);
 
   return result;
 }
@@ skipping 42 matching lines @@
   class_ex.hIconSm = class_ex.hIcon;
   ATOM atom = RegisterClassEx(&class_ex);
   DCHECK(atom);
 
   Singleton<ClassRegistrar>()->RegisterClass(class_info, name, atom);
 
   return name;
 }
 
 }  // namespace app