Revert of Refactor backdrop

ui/aura/client/aura_constants.h

 // 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_AURA_CLIENT_AURA_CONSTANTS_H_
 #define UI_AURA_CLIENT_AURA_CONSTANTS_H_
 
 #include <string>
 
 #include "base/strings/string16.h"
@@ skipping 50 matching lines @@
 // A property key to store if a window was created by a user gesture.
 AURA_EXPORT extern const WindowProperty<bool>* const kCreatedByUserGesture;
 
 // A property key to indicate that a window should show that it deserves
 // attention.
 AURA_EXPORT extern const WindowProperty<bool>* const kDrawAttentionKey;
 
 // A property key to store the focus client on the window.
 AURA_EXPORT extern const WindowProperty<FocusClient*>* const kFocusClientKey;
 
-// A bool property key to specify if the window should have a backdrop window
-// (typically black) that covers the desktop behind the window.
-AURA_EXPORT extern const WindowProperty<bool>* const kHasBackdrop;
-
 // A property key to store the host window of a window. This lets
 // WebContentsViews find the windows that should constrain NPAPI plugins.
 AURA_EXPORT extern const WindowProperty<Window*>* const kHostWindowKey;
 
 // A property key to indicate that a window should be in immersive mode when the
 // window enters the fullscreen mode. The immersive fullscreen mode is slightly
 // different from the normal fullscreen mode by allowing the user to reveal the
 // top portion of the window through a touch / mouse gesture.
 AURA_EXPORT extern const WindowProperty<bool>* const kImmersiveFullscreenKey;
 
@@ skipping 54 matching lines @@
 
 AURA_EXPORT extern const WindowProperty<ui::mojom::WindowType>* const
     kWindowTypeKey;
 
 // Alphabetical sort.
 
 }  // namespace client
 }  // namespace aura
 
 #endif  // UI_AURA_CLIENT_AURA_CONSTANTS_H_