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

content/browser/accessibility/browser_accessibility_manager.cc

Index: content/browser/accessibility/browser_accessibility_manager.cc
diff --git a/content/browser/accessibility/browser_accessibility_manager.cc b/content/browser/accessibility/browser_accessibility_manager.cc
index 17c72919c0bed22102856937886275435aab23e7..a8ca1e5b08d6f58ef9856d707413618d1cb157f9 100644
--- a/content/browser/accessibility/browser_accessibility_manager.cc
+++ b/content/browser/accessibility/browser_accessibility_manager.cc
@@ -452,10 +452,10 @@ void BrowserAccessibilityManager::ActivateFindInPageResult(
 
 BrowserAccessibility* BrowserAccessibilityManager::GetActiveDescendantFocus(
     BrowserAccessibility* focus) {
-  if (!focus)
-    return NULL;
+  if (!focus || !focus->instance_active())

[dmazzoni, 2016/04/18 18:27:03]

We shouldn't ever have to check instance_active() here.

The only time we need to check instance_active is in the implementation of a
native API function, like get_accChild, etc.

When instance_active() is false, we've already removed all references to the
object, it's completely unreachable - the only remaining references are held by
another process.

+    return nullptr;
 
-  int active_descendant_id;
+  int32_t active_descendant_id;
   if (focus->GetIntAttribute(ui::AX_ATTR_ACTIVEDESCENDANT_ID,
                              &active_descendant_id)) {
     BrowserAccessibility* active_descendant =