Make mus_demo_unittests work with multiple root windows

ash/mus/app_launch_unittest.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 "base/bind.h"
 #include "base/command_line.h"
 #include "base/run_loop.h"
 #include "mash/quick_launch/public/interfaces/constants.mojom.h"
 #include "services/service_manager/public/cpp/service_test.h"
 #include "services/ui/public/interfaces/constants.mojom.h"
 #include "services/ui/public/interfaces/window_server_test.mojom.h"
 
 namespace ash {
 namespace mus {
 
-void RunCallback(bool* success, const base::Closure& callback, bool result) {
-  *success = result;
+void RunCallback(uint64_t* root_window_count,
+                 const base::Closure& callback,
+                 uint64_t result) {
+  *root_window_count = result;
   callback.Run();
 }
 
 class AppLaunchTest : public service_manager::test::ServiceTest {
  public:
   AppLaunchTest() : ServiceTest("mash_unittests") {}
   ~AppLaunchTest() override {}
 
  private:
   void SetUp() override {
     base::CommandLine::ForCurrentProcess()->AppendSwitch("use-test-config");
     ServiceTest::SetUp();
   }
 
   DISALLOW_COPY_AND_ASSIGN(AppLaunchTest);
 };
 
 TEST_F(AppLaunchTest, TestQuickLaunch) {
   connector()->Connect("ash");
   connector()->Connect(mash::quick_launch::mojom::kServiceName);
 
   ui::mojom::WindowServerTestPtr test_interface;
   connector()->BindInterface(ui::mojom::kServiceName, &test_interface);
 
   base::RunLoop run_loop;
-  bool success = false;
-  test_interface->EnsureClientHasDrawnWindow(
+  uint64_t root_window_count = 0;
+  test_interface->EnsureClientHasDrawnRootWindows(
       mash::quick_launch::mojom::kServiceName,
-      base::Bind(&RunCallback, &success, run_loop.QuitClosure()));
+      base::Bind(&RunCallback, &root_window_count, run_loop.QuitClosure()));
   run_loop.Run();
-  EXPECT_TRUE(success);
+  EXPECT_EQ(1u, root_window_count);
 }
 
 }  // namespace mus
 }  // namespace ash