mash: Fix crash when closing system tray menu

ash/common/wm/container_finder.cc

 // Copyright 2016 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 "ash/common/wm/container_finder.h"
 
 #include "ash/common/session/session_state_delegate.h"
 #include "ash/common/shell_window_ids.h"
 #include "ash/common/wm/always_on_top_controller.h"
 #include "ash/common/wm/root_window_finder.h"
@@ skipping 42 matching lines @@
 WmWindow* GetContainerFromAlwaysOnTopController(WmWindow* root,
                                                 WmWindow* window) {
   return root->GetRootWindowController()
       ->GetAlwaysOnTopController()
       ->GetContainer(window);
 }
 
 }  // namespace
 
 WmWindow* GetContainerForWindow(WmWindow* window) {
-  WmWindow* container = window->GetParent();
-  while (container && container->GetType() != ui::wm::WINDOW_TYPE_UNKNOWN)
-    container = container->GetParent();
-  return container;
+  WmWindow* parent = window->GetParent();
+  // The first parent with an explicit shell window ID is the container.
+  while (parent && parent->GetShellWindowId() == kShellWindowId_Invalid)
+    parent = parent->GetParent();
+  return parent;
 }
 
 WmWindow* GetDefaultParent(WmWindow* context,
                            WmWindow* window,
                            const gfx::Rect& bounds) {
   WmWindow* target_root = nullptr;
   WmWindow* transient_parent = window->GetTransientParent();
   if (transient_parent) {
     // Transient window should use the same root as its transient parent.
     target_root = transient_parent->GetRootWindow();
@@ skipping 25 matching lines @@
     default:
       NOTREACHED() << "Window " << window->GetShellWindowId()
                    << " has unhandled type " << window->GetType();
       break;
   }
   return nullptr;
 }
 
 }  // namespace wm
 }  // namespace ash