Introduce WindowStateDelegate::ToggleFullscreen

ash/wm/window_state_delegate.h

Index: ash/wm/window_state_delegate.h
diff --git a/ash/wm/window_state_delegate.h b/ash/wm/window_state_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..7b9a8baa3d2cdd8341fc576fe14aef2efb2c90fe
--- /dev/null
+++ b/ash/wm/window_state_delegate.h
@@ -0,0 +1,32 @@
+// Copyright 2013 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 ASH_WM_WINDOW_STATE_DELEGATE_H_
+#define ASH_WM_WINDOW_STATE_DELEGATE_H_
+
+#include "ash/ash_export.h"
+#include "base/basictypes.h"
+
+namespace ash {
+namespace wm {
+class WindowState;
+
+class ASH_EXPORT WindowStateDelegate {
+ public:
+  WindowStateDelegate();
+  virtual ~WindowStateDelegate();
+
+  // Invoked when the user uses Shift+F4/F4 to toggle the window
+  // fullscreen state.  The caller (ash::wm::WindowState) falls backs
+  // to the default implementation if this returns false.
+  virtual bool ToggleFullscreen(WindowState* window_state);
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(WindowStateDelegate);
+};
+
+}  // namespace wm
+}  // namespace ash
+
+#endif  // ASH_WM_WINDOW_STATE_DELEGATE_H_