Make mus_demo_unittests work with multiple root windows

services/ui/demo/mus_demo_unittests.cc

Index: services/ui/demo/mus_demo_unittests.cc
diff --git a/services/ui/demo/mus_demo_unittests.cc b/services/ui/demo/mus_demo_unittests.cc
index 9fdb8107a2c0aff014de2d237164dce0aaecd753..0e1aaa524704ef37a8a86ab884031bfb1c4d8007 100644
--- a/services/ui/demo/mus_demo_unittests.cc
+++ b/services/ui/demo/mus_demo_unittests.cc
@@ -18,8 +18,10 @@ namespace {
 
 const char kTestAppName[] = "mus_demo_unittests";
 
-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();
 }
 
@@ -46,14 +48,16 @@ TEST_F(MusDemoTest, CheckMusDemoDraws) {
   connector()->BindInterface(ui::mojom::kServiceName, &test_interface);
 
   base::RunLoop run_loop;
-  bool success = false;
+  uint64_t root_window_count = 0;
   // TODO(kylechar): Fix WindowServer::CreateTreeForWindowManager so that the
   // WindowTree has the correct name instead of an empty name.
-  test_interface->EnsureClientHasDrawnWindow(
+  // TODO(tonikitoo,fwang): Also fix the WindowTree name for MusDemoExternal.
+  test_interface->EnsureClientHasDrawnRootWindows(
       "",  // WindowTree name is empty.
-      base::Bind(&RunCallback, &success, run_loop.QuitClosure()));
+      base::Bind(&RunCallback, &root_window_count, run_loop.QuitClosure()));
   run_loop.Run();
-  EXPECT_TRUE(success);
+  // TODO(tonikitoo,fwang): Test multiple windows for MusDemoExternal.
+  EXPECT_EQ(1u, root_window_count);
 }
 
 }  // namespace demo