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

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 b3e6613ed10a610f7380ed1c5ff237948b6c536c..f6e5f54b1be3202036260639c399f42153bfca23 100644
--- a/content/browser/accessibility/browser_accessibility_manager_win.cc
+++ b/content/browser/accessibility/browser_accessibility_manager_win.cc
@@ -136,9 +136,27 @@ void BrowserAccessibilityManagerWin::UserIsReloading() {
     MaybeCallNotifyWinEvent(IA2_EVENT_DOCUMENT_RELOAD, GetRoot());
 }
 
+BrowserAccessibility* BrowserAccessibilityManagerWin::GetFocus() {
+  BrowserAccessibility* node = BrowserAccessibilityManager::GetFocus();
+
+  // Combo boxes have an invisible list inside them which tracks the active list

[dmazzoni, 2016/04/29 20:55:54]

Isn't the combo box itself supposed to have activedescendant on it?

Either way, consider moving this to cross-platform code, because we should track
the activedescendant of a combobox on all platforms. If there's something
platform-specific, it should maybe just be a tiny override on Mac that says not
to follow active descendant focus on Mac because it doesn't work that way

+  // item.
+  if (node && node->GetRole() == ui::AX_ROLE_COMBO_BOX) {

[dmazzoni, 2016/04/29 20:55:54]

Same here, only if combo box is editable?

+    BrowserAccessibility* child = node->InternalGetChild(0);
+    if (child && child->GetRole() == ui::AX_ROLE_LIST) {
+      BrowserAccessibility* active_list_item = GetActiveDescendantFocus(child);
+      if (active_list_item != child)
+        return active_list_item;
+    }
+  }
+
+  return GetActiveDescendantFocus(node);
+}
+
 void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
     ui::AXEvent event_type,
     BrowserAccessibility* node) {
+  DCHECK(node);
   BrowserAccessibilityDelegate* root_delegate = GetDelegateFromRootManager();
   if (!root_delegate || !root_delegate->AccessibilityGetAcceleratedWidget()) {
     DLOG(WARNING) << "Not firing AX event because of no root_delegate or hwnd";
@@ -157,9 +175,10 @@ void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
 
   LONG event_id = EVENT_MIN;
   switch (event_type) {
-    case ui::AX_EVENT_ACTIVEDESCENDANTCHANGED:
+    case ui::AX_EVENT_ACTIVEDESCENDANTCHANGED: {
       event_id = IA2_EVENT_ACTIVE_DESCENDANT_CHANGED;
       break;
+    }
     case ui::AX_EVENT_ALERT:
       event_id = EVENT_SYSTEM_ALERT;
       break;
@@ -209,9 +228,6 @@ void BrowserAccessibilityManagerWin::NotifyAccessibilityEvent(
       break;
   }
 
-  if (!node)
-    return;
-
   if (event_id != EVENT_MIN)
     MaybeCallNotifyWinEvent(event_id, node);
 
@@ -238,6 +254,7 @@ bool BrowserAccessibilityManagerWin::CanFireEvents() {
 
 void BrowserAccessibilityManagerWin::FireFocusEvent(
     BrowserAccessibility* node) {
+  DCHECK(node);
   // On Windows, we always fire a FOCUS event on the root of a frame before
   // firing a focus event within that frame.
   if (node->manager() != last_focused_manager_ &&