Improve the notifications sent from AXTree updates.

content/browser/accessibility/browser_accessibility_manager_win.cc

Index: content/browser/accessibility/browser_accessibility_manager_win.cc
diff --git a/content/browser/accessibility/browser_accessibility_manager_win.cc b/content/browser/accessibility/browser_accessibility_manager_win.cc
index b7424870cea93a3dae7302f5b9dc0662539c9b8e..200f832835b8130d79e44a106fe3e8cc541ccc8e 100644
--- a/content/browser/accessibility/browser_accessibility_manager_win.cc
+++ b/content/browser/accessibility/browser_accessibility_manager_win.cc
@@ -262,10 +262,14 @@ void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
   }
 }
 
-void BrowserAccessibilityManagerWin::OnRootChanged(ui::AXNode* new_root) {
-  // In order to make screen readers aware of the new accessibility root,
-  // we need to fire a focus event on it.
-  OnWindowFocused();
+void BrowserAccessibilityManagerWin::OnAtomicUpdateFinished(
+    bool root_changed,
+    const std::vector<ui::AXTreeDelegate::Change>& changes) {
+  if (root_changed) {
+    // In order to make screen readers aware of the new accessibility root,
+    // we need to fire a focus event on it.
+    OnWindowFocused();
+  }
 }
 
 void BrowserAccessibilityManagerWin::TrackScrollingObject(