Reland Ensure WebView notifies desktop automation on creation, destruction, and change

ui/views/accessibility/ax_widget_obj_wrapper.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/views/accessibility/ax_widget_obj_wrapper.h"
 
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/views/accessibility/ax_aura_obj_cache.h"
 #include "ui/views/accessibility/ax_aura_obj_wrapper.h"
 #include "ui/views/widget/widget.h"
 
 namespace views {
 
 AXWidgetObjWrapper::AXWidgetObjWrapper(Widget* widget) : widget_(widget) {
   widget->AddObserver(this);
   widget->AddRemovalsObserver(this);
 }
 
 AXWidgetObjWrapper::~AXWidgetObjWrapper() {
-  widget_->RemoveObserver(this);
-  widget_->RemoveRemovalsObserver(this);
+  if (!AXAuraObjCache::GetInstance()->is_destroying()) {
+    widget_->RemoveObserver(this);
+    widget_->RemoveRemovalsObserver(this);
+  }
   widget_ = NULL;
 }
 
 AXAuraObjWrapper* AXWidgetObjWrapper::GetParent() {
   return AXAuraObjCache::GetInstance()->GetOrCreate(widget_->GetNativeView());
 }
 
 void AXWidgetObjWrapper::GetChildren(
     std::vector<AXAuraObjWrapper*>* out_children) {
   out_children->push_back(
@@ skipping 14 matching lines @@
 
 void AXWidgetObjWrapper::OnWidgetDestroying(Widget* widget) {
   AXAuraObjCache::GetInstance()->Remove(widget);
 }
 
 void AXWidgetObjWrapper::OnWillRemoveView(Widget* widget, View* view) {
   AXAuraObjCache::GetInstance()->Remove(view);
 }
 
 }  // namespace views