Clean up code and logic related to platform accessibility node destruction.

ui/accessibility/platform/ax_platform_node_base.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_base.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "ui/accessibility/ax_node_data.h"
 #include "ui/accessibility/platform/ax_platform_node_delegate.h"
 
@@ skipping 28 matching lines @@
 gfx::NativeViewAccessible AXPlatformNodeBase::ChildAtIndex(int index) {
   CHECK(delegate_);
   return delegate_->ChildAtIndex(index);
 }
 
 // AXPlatformNode overrides.
 
 void AXPlatformNodeBase::Destroy() {
   AXPlatformNode::Destroy();
   delegate_ = nullptr;
+  Dispose();
+}
+
+void AXPlatformNodeBase::Dispose() {
   delete this;
 }
 
 gfx::NativeViewAccessible AXPlatformNodeBase::GetNativeViewAccessible() {
   return nullptr;
 }
 
 AXPlatformNodeDelegate* AXPlatformNodeBase::GetDelegate() const {
   return delegate_;
 }
@@ skipping 123 matching lines @@
     ui::AXStringAttribute attribute,
     base::string16* value) const {
   CHECK(delegate_);
   return GetData().GetString16Attribute(attribute, value);
 }
 
 AXPlatformNodeBase::AXPlatformNodeBase() {
 }
 
 AXPlatformNodeBase::~AXPlatformNodeBase() {
+  CHECK(!delegate_);
 }
 
 // static
 AXPlatformNodeBase* AXPlatformNodeBase::FromNativeViewAccessible(
     gfx::NativeViewAccessible accessible) {
   return static_cast<AXPlatformNodeBase*>(
       AXPlatformNode::FromNativeViewAccessible(accessible));
 }
 
 }  // namespace ui