Re-land: Resurrect Aura Linux accessibility.

ui/views/accessibility/native_view_accessibility.cc

 // Copyright (c) 2013 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/views/accessibility/native_view_accessibility.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "ui/accessibility/ax_view_state.h"
 #include "ui/events/event_utils.h"
 #include "ui/views/controls/native/native_view_host.h"
 #include "ui/views/view.h"
 #include "ui/views/widget/widget.h"
 
 namespace views {
 
-#if !defined(OS_WIN)
+#if !defined(OS_WIN) && !(defined(OS_LINUX) && !defined(OS_CHROMEOS))
 // static
 NativeViewAccessibility* NativeViewAccessibility::Create(View* view) {
   return new NativeViewAccessibility(view);
 }
 #endif
 
 NativeViewAccessibility::NativeViewAccessibility(View* view)
     : view_(view),
       parent_widget_(nullptr),
-      ax_node_(ui::AXPlatformNode::Create(this)) {
+      ax_node_(nullptr) {
+  ax_node_ = ui::AXPlatformNode::Create(this);
 }
 
 NativeViewAccessibility::~NativeViewAccessibility() {
   if (ax_node_)
     ax_node_->Destroy();
   if (parent_widget_)
     parent_widget_->RemoveObserver(this);
 }
 
 gfx::NativeViewAccessible NativeViewAccessibility::GetNativeObject() {
@@ skipping 205 matching lines @@
               child_widget_platform_node->GetDelegate());
       if (child_widget_view_accessibility->parent_widget() != widget)
         child_widget_view_accessibility->SetParentWidget(widget);
     }
 
     result_child_widgets->push_back(child_widget);
   }
 }
 
 }  // namespace views