1 files changed, 61 insertions, 0 deletions
diff --git a/ui/gfx/win/singleton_hwnd.h b/ui/gfx/win/singleton_hwnd.h
new file mode 100644
index 0000000..96af6e7
--- /dev/null
+++ b/ui/gfx/win/singleton_hwnd.h
@@ -0,0 +1,61 @@
+// 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_GFX_WIN_SINGLETON_HWND_H_
+#define UI_GFX_WIN_SINGLETON_HWND_H_
+
+#include <windows.h>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/callback_forward.h"
+#include "base/observer_list.h"
+#include "ui/gfx/win/window_impl.h"
+
+template<typename T> struct DefaultSingletonTraits;
+
+namespace gfx {
+
+// Singleton message-only HWND that allows interested clients to receive WM_*
+// notifications.
+class SingletonHwnd : public WindowImpl {
+ public:
+  static SingletonHwnd* GetInstance();
+
+  // Observer interface for receiving Windows WM_* notifications.
+  class Observer {
+   public:
+    virtual void OnWndProc(HWND hwnd,
+                           UINT message,
+                           WPARAM wparam,
+                           LPARAM lparam) = 0;
+  };
+
+  // Add/remove observer to receive WM_* notifications.
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  // Windows callback for WM_* notifications.
+  virtual BOOL ProcessWindowMessage(HWND window,
+                                    UINT message,
+                                    WPARAM wparam,
+                                    LPARAM lparam,
+                                    LRESULT& result,
+                                    DWORD msg_map_id) OVERRIDE;
+
+ private:
+  friend struct DefaultSingletonTraits<SingletonHwnd>;
+
+  SingletonHwnd();
+  ~SingletonHwnd();
+
+  // List of registered observers.
+  ObserverList<Observer> observer_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(SingletonHwnd);
+};
+
+}  // namespace gfx
+
+#endif  // UI_GFX_WIN_SINGLETON_HWND_H_