[Aura] Support always-on-top top level window.

ui/aura/window.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_WINDOW_H_
 #define UI_AURA_WINDOW_H_
 #pragma once
 
 #include <map>
 #include <vector>
@@ skipping 38 matching lines @@
 class FocusManager;
 }
 
 // Aura window implementation. Interesting events are sent to the
 // WindowDelegate.
 // TODO(beng): resolve ownership.
 class AURA_EXPORT Window : public ui::LayerDelegate {
  public:
   typedef std::vector<Window*> Windows;
 
+  // Property names.
+  static const char kPropAlwaysOnTop[];  // boolean, default is false.

[oshima, 2011/11/01 18:35:21]

move this to ui/aura/aura_contents.h 

[xiyuan, 2011/11/02 23:26:32]

Done.

+
   explicit Window(WindowDelegate* delegate);
   virtual ~Window();
 
   void Init(ui::Layer::LayerType layer_type);
 
   // A type is used to identify a class of Windows and customize behavior such
   // as event handling and parenting. The value can be any of those in
   // window_types.h or a user defined value.
   int type() const { return type_; }
   void SetType(int type);
@@ skipping 286 matching lines @@
   // TODO(oshima): Consolidcate ViewProp and aura::window property
   // implementation.
   std::map<const char*, ui::ViewProp*> prop_map_;
 
   DISALLOW_COPY_AND_ASSIGN(Window);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_WINDOW_H_