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

ui/accessibility/platform/ax_platform_node_base.cc

Index: ui/accessibility/platform/ax_platform_node_base.cc
diff --git a/ui/accessibility/platform/ax_platform_node_base.cc b/ui/accessibility/platform/ax_platform_node_base.cc
index 4937e4d317876f64573f982ae687bddeef132d16..b3aa9d43771d26f50be36619eec2cd636c414601 100644
--- a/ui/accessibility/platform/ax_platform_node_base.cc
+++ b/ui/accessibility/platform/ax_platform_node_base.cc
@@ -46,6 +46,10 @@ gfx::NativeViewAccessible AXPlatformNodeBase::ChildAtIndex(int index) {
 void AXPlatformNodeBase::Destroy() {
   AXPlatformNode::Destroy();
   delegate_ = nullptr;
+  Dispose();
+}
+
+void AXPlatformNodeBase::Dispose() {
   delete this;
 }
 
@@ -189,6 +193,7 @@ AXPlatformNodeBase::AXPlatformNodeBase() {
 }
 
 AXPlatformNodeBase::~AXPlatformNodeBase() {
+  CHECK(!delegate_);
 }
 
 // static