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

ui/base/clipboard/clipboard.h

Index: ui/base/clipboard/clipboard.h
diff --git a/ui/base/clipboard/clipboard.h b/ui/base/clipboard/clipboard.h
index a827d2607088f8f4d5c6a4cd874d06a4a63c584f..816e0450ecfc5e6616536b7ef0aba5b207e49f12 100644
--- a/ui/base/clipboard/clipboard.h
+++ b/ui/base/clipboard/clipboard.h
@@ -31,7 +31,7 @@
 #include "base/android/scoped_java_ref.h"
 #endif
 
-#if defined(USE_AURA) && defined(USE_X11)
+#if (defined(USE_AURA) && defined(USE_X11)) || defined(OS_WIN)
 #include "base/memory/scoped_ptr.h"
 #endif
 
@@ -315,6 +315,8 @@ class UI_EXPORT Clipboard : NON_EXPORTED_BASE(public base::ThreadChecker) {
 #endif
 
  private:
+  class ClipboardWindow;
+
   FRIEND_TEST_ALL_PREFIXES(ClipboardTest, SharedBitmapTest);
   FRIEND_TEST_ALL_PREFIXES(ClipboardTest, EmptyHTMLTest);
   friend class ClipboardTest;
@@ -364,10 +366,8 @@ class UI_EXPORT Clipboard : NON_EXPORTED_BASE(public base::ThreadChecker) {
   HWND GetClipboardWindow() const;
 
   // Mark this as mutable so const methods can still do lazy initialization.
-  mutable HWND clipboard_owner_;
+  mutable scoped_ptr<ClipboardWindow> 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