make menus, bubbles, etc. top level windows on aura

ui/aura/client/animation_host.h

+// 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 UI_AURA_CLIENT_ANIMATION_HOST_H_
+#define UI_AURA_CLIENT_ANIMATION_HOST_H_
+
+#include "base/compiler_specific.h"
+#include "ui/aura/aura_export.h"
+
+namespace gfx {
+class Rect;
+}
+
+namespace aura {
+class Window;
+namespace client {
+
+class AURA_EXPORT AnimationHost {
+ public:
+  // Ensure the host window is at least this large so that transitions have
+  // sufficient space.
+  virtual void SetHostTransitionBounds(const gfx::Rect& bounds) = 0;
+
+  // Called after the window has faded out on a hide.
+  virtual void OnWindowHidingAnimationCompleted() = 0;
+
+ protected:
+  virtual ~AnimationHost() {}
+};
+
+AURA_EXPORT void SetAnimationHost(Window* window,
+                                  AnimationHost* animation_host);
+AURA_EXPORT AnimationHost* GetAnimationHost(Window* window);
+
+}  // namespace client
+}  // namespace aura
+
+#endif  // UI_AURA_CLIENT_ANIMATION_HOST_H_