Move some more WM functionality down into ash.

ui/aura_shell/window_frame.h

-// Copyright (c) 2011 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_AURA_SHELL_WINDOW_FRAME_H_
-#define UI_AURA_SHELL_WINDOW_FRAME_H_
-#pragma once
-
-#include "ui/aura_shell/aura_shell_export.h"
-
-namespace aura_shell {
-
-// aura::Window property name for a pointer to the WindowFrame interface.
-AURA_SHELL_EXPORT extern const char* const kWindowFrameKey;
-
-// Interface for clients implementing a window frame.  Implementors should
-// add a pointer to this interface to each aura::Window, using the key above.
-class AURA_SHELL_EXPORT WindowFrame {
- public:
-  virtual ~WindowFrame() {}
-
-  // Called when the mouse enters or exits a top-level window.
-  virtual void OnWindowHoverChanged(bool hovered) = 0;
-};
-
-}  // namespace aura_shell
-
-#endif  // UI_AURA_SHELL_WINDOW_FRAME_H_