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

ui/accessibility/platform/aura_window_properties.cc

Index: ui/accessibility/platform/aura_window_properties.cc
diff --git a/ui/accessibility/platform/aura_window_properties.cc b/ui/accessibility/platform/aura_window_properties.cc
deleted file mode 100644
index 146ad75b77e8ec6738db2abb1631ebac956776d0..0000000000000000000000000000000000000000
--- a/ui/accessibility/platform/aura_window_properties.cc
+++ /dev/null
@@ -1,15 +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.
-
-#include "ui/accessibility/platform/aura_window_properties.h"
-
-#include "ui/base/class_property.h"
-
-namespace ui {
-
-DEFINE_UI_CLASS_PROPERTY_KEY(AXTreeIDRegistry::AXTreeID,
-                             kChildAXTreeID,
-                             AXTreeIDRegistry::kNoAXTreeID);
-
-}  // namespace ui