Revert of Implement NativeViewAccessibilityWin using AXPlatformNodeWin.

ui/accessibility/platform/ax_platform_node.cc

 // Copyright 2014 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/ax_platform_node.h"
 
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/accessibility/platform/ax_platform_node_delegate.h"
 
 namespace ui {
 
-#if !defined(OS_MACOSX) && !defined(OS_WIN)
+#if !defined(OS_MACOSX)
 // static
 AXPlatformNode* AXPlatformNode::Create(AXPlatformNodeDelegate* delegate) {
-  return nullptr;
+  return NULL;
 }
 #endif
 
-#if !defined(OS_WIN)
-// This is the default implementation for platforms where native views
-// accessibility is unsupported or unfinished.
-//
-// static
-AXPlatformNode* AXPlatformNode::FromNativeViewAccessible(
-    gfx::NativeViewAccessible accessible) {
-  return nullptr;
-}
-#endif
-
 AXPlatformNode::AXPlatformNode() {
 }
 
 AXPlatformNode::~AXPlatformNode() {
 }
 
 }  // namespace ui