Uses the activedescendant_changed event received from Blink to fire the right focus event

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 e77833cf60232bd30b93cc46828ab943579808dc..9ea6ab3d9af1161d7de95b6db0d6d45bbcf480e5 100644
--- a/content/browser/accessibility/browser_accessibility.cc
+++ b/content/browser/accessibility/browser_accessibility.cc
@@ -131,10 +131,9 @@ bool BrowserAccessibility::IsTextOnlyObject() const {
 
 BrowserAccessibility* BrowserAccessibility::PlatformGetChild(
     uint32_t child_index) const {
-  DCHECK_LT(child_index, PlatformChildCount());
   BrowserAccessibility* result = nullptr;
 
-  if (HasIntAttribute(ui::AX_ATTR_CHILD_TREE_ID)) {
+  if (child_index == 0 && HasIntAttribute(ui::AX_ATTR_CHILD_TREE_ID)) {
     BrowserAccessibilityManager* child_manager =
         BrowserAccessibilityManager::FromID(
             GetIntAttribute(ui::AX_ATTR_CHILD_TREE_ID));