Don't store raw pointers in BrowserAccessibilityManager::tree_changes_

content/browser/accessibility/browser_accessibility_manager.h

Index: content/browser/accessibility/browser_accessibility_manager.h
diff --git a/content/browser/accessibility/browser_accessibility_manager.h b/content/browser/accessibility/browser_accessibility_manager.h
index 6bd0d1b1d1c04f39ba14d51e7013f64c28e5a224..3f7c5ca0007a8fcf71120f0a00b6d2240a13e37b 100644
--- a/content/browser/accessibility/browser_accessibility_manager.h
+++ b/content/browser/accessibility/browser_accessibility_manager.h
@@ -441,10 +441,9 @@ class CONTENT_EXPORT BrowserAccessibilityManager : public ui::AXTreeDelegate {
   // A mapping from a node id to its wrapper of type BrowserAccessibility.
   base::hash_map<int32_t, BrowserAccessibility*> id_wrapper_map_;
 
-  // A list of accessibility events to fire based on changes to the
-  // accessibility tree. Only used within the scope of one call to
-  // OnAccessibilityEvents, so it's safe to store raw pointers.
-  std::vector<std::pair<ui::AXEvent, BrowserAccessibility*>> tree_events_;
+  // A queue of accessibility events to fire based on changes to the
+  // accessibility tree. Each one is an event and a node id.
+  std::vector<std::pair<ui::AXEvent, int32_t>> tree_events_;
 
   // True if the user has initiated a navigation to another page.
   bool user_is_navigating_away_;