chromeos: delete WindowTreeFactory before asserting no WindowTrees

WindowTreeFactory owns any WindowTrees that were created by way of
ui::mojom::WindowTreeFactory. So, WindowTreeFactory needs to be deleted before
the DCHECK that there are no more WindowTrees.

BUG=854336
TEST=covered by test

Change-Id: Idba2928244721579e694b434415b95cbbdf4b360
Reviewed-on: https://chromium-review.googlesource.com/1107136
Commit-Queue: Scott Violet <sky@chromium.org>
Reviewed-by: James Cook <jamescook@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568859}

services/ui/ws2/BUILD.gn

@@ -163,6 +163,7 @@ source_set("tests") {
     "embedding_unittest.cc",
     "focus_handler_unittest.cc",
     "screen_provider_unittest.cc",
+    "window_service_unittest.cc",
     "window_tree_client_unittest.cc",
     "window_tree_unittest.cc",
   ]
@@ -174,6 +175,7 @@ source_set("tests") {
     "//components/viz/common",
     "//mojo/public/cpp/bindings",
     "//services/service_manager/public/cpp:service_test_support",
+    "//services/service_manager/public/cpp/test:test_support",
     "//services/service_manager/public/mojom",
     "//services/ui/common:task_runner_test_base",
     "//services/ui/public/cpp",

services/ui/ws2/window_service.cc

@@ -36,6 +36,9 @@ WindowService::WindowService(
 }
 
 WindowService::~WindowService() {
+  // WindowTreeFactory owns WindowTrees created by way of WindowTreeFactory.
+  // Deleting it should ensure there are no WindowTrees left.
+  window_tree_factory_.reset();
   DCHECK(window_trees_.empty());
 }
 

services/ui/ws2/window_service_unittest.cc

+// Copyright 2018 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 "services/ui/ws2/window_service.h"
+
+#include <memory>
+
+#include "base/run_loop.h"
+#include "services/service_manager/public/cpp/connector.h"
+#include "services/service_manager/public/cpp/test/test_connector_factory.h"
+#include "services/ui/public/interfaces/constants.mojom.h"
+#include "services/ui/public/interfaces/window_tree.mojom.h"
+#include "services/ui/ws2/gpu_interface_provider.h"
+#include "services/ui/ws2/window_service_test_setup.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace ui {
+namespace ws2 {
+
+TEST(WindowServiceTest, DeleteWithClients) {
+  // Use |test_setup| to configure aura and other state.
+  WindowServiceTestSetup test_setup;
+
+  // Create another WindowService.
+  TestWindowServiceDelegate test_window_service_delegate;
+  std::unique_ptr<WindowService> window_service_ptr =
+      std::make_unique<WindowService>(&test_window_service_delegate, nullptr,
+                                      test_setup.focus_controller());
+  WindowService* window_service = window_service_ptr.get();
+  std::unique_ptr<service_manager::TestConnectorFactory> factory =
+      service_manager::TestConnectorFactory::CreateForUniqueService(
+          std::move(window_service_ptr));
+  std::unique_ptr<service_manager::Connector> connector =
+      factory->CreateConnector();
+
+  // Connect to |window_service| and ask for a new WindowTree.
+  ui::mojom::WindowTreeFactoryPtr window_tree_factory;
+  connector->BindInterface(ui::mojom::kServiceName, &window_tree_factory);
+  ui::mojom::WindowTreePtr window_tree;
+  ui::mojom::WindowTreeClientPtr client;
+  mojom::WindowTreeClientRequest client_request = MakeRequest(&client);
+  window_tree_factory->CreateWindowTree(MakeRequest(&window_tree),
+                                        std::move(client));
+
+  // Use FlushForTesting() to ensure WindowService processes the request.
+  window_tree_factory.FlushForTesting();
+
+  // There should be at least one WindowTree.
+  EXPECT_FALSE(window_service->window_trees().empty());
+
+  // Destroying the |window_service| should remove all the WindowTrees and
+  // ensure a DCHECK isn't hit in ~WindowTree.
+}
+
+}  // namespace ws2
+}  // namespace ui