ui::Clipboard now uses base::win::MessageWindow to create a message-only window on Windows.

ui/base/clipboard/clipboard.h

 // 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.
 
 #ifndef UI_BASE_CLIPBOARD_CLIPBOARD_H_
 #define UI_BASE_CLIPBOARD_CLIPBOARD_H_
 
 #include <map>
 #include <string>
 #include <vector>
 
 #include "base/compiler_specific.h"
 #include "base/gtest_prod_util.h"
+#include "base/memory/scoped_ptr.h"
 #include "base/memory/shared_memory.h"
 #include "base/process.h"
 #include "base/strings/string16.h"
 #include "base/threading/platform_thread.h"
 #include "base/threading/thread_checker.h"
 #include "ui/base/ui_export.h"
 
 #if defined(TOOLKIT_GTK)
 #include <gdk/gdk.h>
 #endif
 
 #if defined(OS_WIN)
 #include <objidl.h>
 #elif defined(OS_ANDROID)
 #include <jni.h>
 
 #include "base/android/jni_android.h"
 #include "base/android/scoped_java_ref.h"
 #endif
 
 #if defined(USE_AURA) && defined(USE_X11)
 #include "base/memory/scoped_ptr.h"
 #endif
 
 namespace base {
 class FilePath;
-}
+
+namespace win {
+class MessageWindow;
+}  // namespace win
+}  // namespace base
 
 namespace gfx {
 class Size;
 }
 
 class SkBitmap;
 
 #if defined(TOOLKIT_GTK)
 typedef struct _GtkClipboard GtkClipboard;
 #endif
@@ skipping 307 matching lines @@
                                            std::string* url);
 
   // Free a handle depending on its type (as intuited from format)
   static void FreeData(unsigned int format, HANDLE data);
 
   // Return the window that should be the clipboard owner, creating it
   // if neccessary.  Marked const for lazily initialization by const methods.
   HWND GetClipboardWindow() const;
 
   // Mark this as mutable so const methods can still do lazy initialization.
-  mutable HWND clipboard_owner_;
+  mutable scoped_ptr<base::win::MessageWindow> clipboard_owner_;
 
-  // True if we can create a window.
-  bool create_window_;
 #elif defined(TOOLKIT_GTK)
   // The public API is via WriteObjects() which dispatches to multiple
   // Write*() calls, but on GTK we must write all the clipboard types
   // in a single GTK call.  To support this we store the current set
   // of data we intend to put on the clipboard on clipboard_data_ as
   // WriteObjects is running, and then at the end call SetGtkClipboard
   // which replaces whatever is on the system clipboard with the
   // contents of clipboard_data_.
 
  public:
@@ skipping 18 matching lines @@
   class AuraX11Details;
   scoped_ptr<AuraX11Details> aurax11_details_;
 #endif
 
   DISALLOW_COPY_AND_ASSIGN(Clipboard);
 };
 
 }  // namespace ui
 
 #endif  // UI_BASE_CLIPBOARD_CLIPBOARD_H_