chromeos: makes it possible for windows to outlive WindowTreeClient

ui/aura/test/aura_test_helper.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_helper.h"
 
 #include "base/command_line.h"
 #include "base/memory/ptr_util.h"
 #include "base/run_loop.h"
 #include "ui/aura/client/default_capture_client.h"
@@ skipping 68 matching lines @@
 }
 
 void AuraTestHelper::EnableMusWithWindowTreeClient(
     WindowTreeClient* window_tree_client) {
   DCHECK(!setup_called_);
   DCHECK_EQ(Mode::LOCAL, mode_);
   mode_ = Mode::MUS;
   window_tree_client_ = window_tree_client;
 }
 
+void AuraTestHelper::DeleteWindowTreeClient() {
+  window_tree_client_setup_.reset();
+  window_tree_client_ = nullptr;
+}
+
 void AuraTestHelper::SetUp(ui::ContextFactory* context_factory,
                            ui::ContextFactoryPrivate* context_factory_private) {
   setup_called_ = true;
 
   if (mode_ != Mode::MUS) {
     // Assume if an explicit WindowTreeClient was created then a WmState was
     // already created.
     wm_state_ = base::MakeUnique<wm::WMState>();
   }
   // Needs to be before creating WindowTreeClient.
@@ skipping 66 matching lines @@
 
     window_tree_client_setup_.reset();
     focus_client_.reset();
     capture_client_.reset();
   }
   ui::GestureRecognizer::Reset();
   ui::ShutdownInputMethodForTesting();
 
   if (env_)
     env_.reset();
-  else
-    EnvTestHelper().SetWindowTreeClient(nullptr);
   wm_state_.reset();
 }
 
 void AuraTestHelper::RunAllPendingInMessageLoop() {
   // TODO(jbates) crbug.com/134753 Find quitters of this RunLoop and have them
   //              use run_loop.QuitClosure().
   base::RunLoop run_loop;
   run_loop.RunUntilIdle();
 }
 
@@ skipping 13 matching lines @@
   window_tree_client_setup_ = base::MakeUnique<TestWindowTreeClientSetup>();
   window_tree_client_setup_->InitForWindowManager(window_tree_delegate_,
                                                   window_manager_delegate_);
   window_tree_client_ = window_tree_client_setup_->window_tree_client();
   window_tree_client_->capture_synchronizer()->AttachToCaptureClient(
       capture_client_.get());
 }
 
 }  // namespace test
 }  // namespace aura