BrowserAccessibility should own a AXPlatformNode.

content/browser/accessibility/browser_accessibility.cc

Index: content/browser/accessibility/browser_accessibility.cc
diff --git a/content/browser/accessibility/browser_accessibility.cc b/content/browser/accessibility/browser_accessibility.cc
index 8141dd2f8616e52ed29ceb53119739f15f296b4a..15ebe61a16bcebda54167ab700d8a24eeb7074d0 100644
--- a/content/browser/accessibility/browser_accessibility.cc
+++ b/content/browser/accessibility/browser_accessibility.cc
@@ -46,6 +46,8 @@ BrowserAccessibility::BrowserAccessibility()
 BrowserAccessibility::~BrowserAccessibility() {
   if (unique_id_)
     g_unique_id_map.Get().erase(unique_id_);
+  if (platform_node_)
+    platform_node_->Destroy();
 }
 
 // static
@@ -61,6 +63,7 @@ void BrowserAccessibility::Init(BrowserAccessibilityManager* manager,
     ui::AXNode* node) {
   manager_ = manager;
   node_ = node;
+  platform_node_ = ui::AXPlatformNode::Create(this);
 }
 
 bool BrowserAccessibility::PlatformIsLeaf() const {