Get mus_ws_unittests working with Ozone X11.

services/ui/ws/window_manager_client_unittest.cc

Index: services/ui/ws/window_manager_client_unittest.cc
diff --git a/services/ui/ws/window_manager_client_unittest.cc b/services/ui/ws/window_manager_client_unittest.cc
index 6362f4cc782fe8491f1766199e99935b1e6e0335..075b70b25f738c20080ccdabcdaa045004803972 100644
--- a/services/ui/ws/window_manager_client_unittest.cc
+++ b/services/ui/ws/window_manager_client_unittest.cc
@@ -353,6 +353,12 @@ class WindowServerTest : public WindowServerTestBase {
       EXPECT_TRUE(WindowServerTestBase::QuitRunLoop());
   }
 
+  // mojo::test::ServiceTest::
+  std::unique_ptr<base::MessageLoop> CreateMessageLoop() override {
+    // The window server is expected to run with a TYPE_UI message loop.
+    return base::MakeUnique<base::MessageLoop>(base::MessageLoop::TYPE_UI);
+  }
+
   std::unique_ptr<EmbedDetails> embed_details_;
 
   std::unique_ptr<ClientAreaChange> client_area_change_;