Revert the if -> DCHECK change

athena/wm/window_list_provider_impl.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "athena/wm/window_list_provider_impl.h"
 
 #include <algorithm>
 
 #include "athena/athena_export.h"
 #include "athena/wm/public/window_list_provider_observer.h"
@@ skipping 79 matching lines @@
 
 void WindowListProviderImpl::RecreateWindowList() {
   window_list_.clear();
   for (auto* window : container_->children()) {
     if (window->GetProperty(kManagedKey))
       window_list_.push_back(window);
   }
 }
 
 void WindowListProviderImpl::OnWindowAdded(aura::Window* window) {
-  DCHECK_EQ(window->parent(), container_);
-  if (!IsValidWindow(window))
+  if (!IsValidWindow(window) || window->parent() != container_)
     return;
 
   window->SetProperty(kManagedKey, true);
   RecreateWindowList();
   DCHECK(IsWindowInList(window));
   window->AddObserver(this);
   FOR_EACH_OBSERVER(
       WindowListProviderObserver, observers_, OnWindowAddedToList(window));
 }
 
@@ skipping 17 matching lines @@
   if (window == container_)
     return;
   DCHECK(IsWindowInList(window));
   RecreateWindowList();
   // Inform our listeners that the stacking has been changed.
   FOR_EACH_OBSERVER(
       WindowListProviderObserver, observers_, OnWindowStackingChangedInList());
 }
 
 }  // namespace athena