chromeos: makes it possible for windows to outlive WindowTreeClient

ui/aura/test/aura_test_base.cc

 // Copyright (c) 2012 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 "ui/aura/test/aura_test_base.h"
 
 #include "base/memory/ptr_util.h"
 #include "ui/aura/client/window_parenting_client.h"
 #include "ui/aura/mus/property_utils.h"
 #include "ui/aura/mus/window_tree_client.h"
@@ skipping 106 matching lines @@
   window->SetBounds(gfx::Rect(0, 0, 100, 100));
   window->Show();
   return window;
 }
 
 void AuraTestBase::EnableMusWithTestWindowTree() {
   DCHECK(!setup_called_);
   use_mus_ = true;
 }
 
+void AuraTestBase::DeleteWindowTreeClient() {
+  DCHECK(use_mus_);
+  helper_->DeleteWindowTreeClient();
+}
+
 void AuraTestBase::ConfigureBackend(BackendType type) {
   if (type == BackendType::MUS)
     EnableMusWithTestWindowTree();
 }
 
 void AuraTestBase::RunAllPendingInMessageLoop() {
   helper_->RunAllPendingInMessageLoop();
 }
 
 void AuraTestBase::ParentWindow(Window* window) {
@@ skipping 119 matching lines @@
 
 AuraTestBaseMus::~AuraTestBaseMus() {}
 
 void AuraTestBaseMus::SetUp() {
   ConfigureBackend(test::BackendType::MUS);
   AuraTestBase::SetUp();
 }
 
 }  // namespace test
 }  // namespace aura