Revert of Add a window property to associate RWHVA with its child AX tree ID

ui/accessibility/platform/aura_window_properties.h

Index: ui/accessibility/platform/aura_window_properties.h
diff --git a/ui/accessibility/platform/aura_window_properties.h b/ui/accessibility/platform/aura_window_properties.h
deleted file mode 100644
index 8c8ea138c3da9c486cee51a83a7ce19d6146108e..0000000000000000000000000000000000000000
--- a/ui/accessibility/platform/aura_window_properties.h
+++ /dev/null
@@ -1,19 +0,0 @@
-// Copyright 2017 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_ACCESSIBILITY_PLATFORM_AURA_WINDOW_PROPERTIES_H_
-#define UI_ACCESSIBILITY_PLATFORM_AURA_WINDOW_PROPERTIES_H_
-
-#include "ui/accessibility/ax_export.h"
-#include "ui/accessibility/ax_tree_id_registry.h"
-#include "ui/aura/window.h"
-
-namespace ui {
-
-AX_EXPORT extern const aura::WindowProperty<AXTreeIDRegistry::AXTreeID>* const
-    kChildAXTreeID;
-
-}  // namespace ui
-
-#endif  // UI_ACCESSIBILITY_PLATFORM_AURA_WINDOW_PROPERTIES_H_