Update desktop tree when Aura windows are removed.

ui/views/accessibility/ax_aura_obj_cache.cc

Index: ui/views/accessibility/ax_aura_obj_cache.cc
diff --git a/ui/views/accessibility/ax_aura_obj_cache.cc b/ui/views/accessibility/ax_aura_obj_cache.cc
index 28162c3092e9aed129ebf9c9e096bd799cc432fa..7107da3f07ca7b7e426bc84980e16aa555972f76 100644
--- a/ui/views/accessibility/ax_aura_obj_cache.cc
+++ b/ui/views/accessibility/ax_aura_obj_cache.cc
@@ -74,8 +74,19 @@ void AXAuraObjCache::Remove(Widget* widget) {
     RemoveViewSubtree(widget->GetRootView());
 }
 
-void AXAuraObjCache::Remove(aura::Window* window) {
+void AXAuraObjCache::Remove(aura::Window* window, bool notify) {
+  int id = GetIDInternal(window, window_to_id_map_);
+  AXAuraObjWrapper* obj = nullptr;
+  if (id != -1) {

[dmazzoni, 2016/08/31 16:33:50]

This check isn't necessary, right? You can still call Get(-1) and it will return
nullptr.

I think this would be more clear, if RemoveInternal doesn't affect |obj|:

AXAuraObjWrapper* obj = Get(id);
RemoveInternal(window, window_to_id_map_);
if (notify && delegate_)
  delegate_->OnChildWindowRemoved(obj ? obj->GetParent() : nullptr);

Alternatively, how about:

AXAuraObjWrapper* window_obj = Get(id);
AXAuraObjWrapper* window_parent_obj = window_obj ? window_obj->GetParent() :
nullptr;
RemoveInternal(window, window_to_id_map_);
if (notify && delegate_)
  delegate_->OnChildWindowRemoved(window_parent_obj);

[David Tseng, 2016/08/31 21:06:42]

Done.

+    obj = Get(id);
+    if (obj)
+      obj = obj->GetParent();
+  }
+
   RemoveInternal(window, window_to_id_map_);
+
+  if (notify && delegate_)
+    delegate_->OnChildWindowRemoved(obj);
 }
 
 AXAuraObjWrapper* AXAuraObjCache::Get(int32_t id) {
@@ -117,8 +128,8 @@ AXAuraObjWrapper* AXAuraObjCache::GetFocus() {
 AXAuraObjCache::AXAuraObjCache()
     : current_id_(1),
       focus_client_(nullptr),
-      is_destroying_(false) {
-}
+      is_destroying_(false),
+      delegate_(nullptr) {}
 
 AXAuraObjCache::~AXAuraObjCache() {
   is_destroying_ = true;