chromeos: fix ash unittest for changes to mojo

This test is creating an aura::Window and then embedding another client in
it. When this happens it is expected that clients set the type before doing
this.

I'm sending this to make sure we don't block some work being done to mojo. I
think the real fix is to remove EMBED_IN_OWNER (there is a bug filed on it).

BUG=872071
TEST=test only change

Change-Id: I6e0f6c5584ea9ec19b0e09fe944a83187a9f5ebf
Reviewed-on: https://chromium-review.googlesource.com/1169695Reviewed-by: Xiyuan Xia <xiyuan@chromium.org>
Commit-Queue: Scott Violet <sky@chromium.org>
Cr-Commit-Position: refs/heads/master@{#581922}

ash/ash_service_unittest.cc

@@ -17,6 +17,7 @@
 #include "services/ui/public/interfaces/window_manager.mojom.h"
 #include "services/ui/public/interfaces/window_tree.mojom.h"
 #include "services/ui/public/interfaces/window_tree_constants.mojom.h"
+#include "ui/aura/client/aura_constants.h"
 #include "ui/aura/env.h"
 #include "ui/aura/mus/property_converter.h"
 #include "ui/aura/mus/window_tree_client.h"
@@ -117,6 +118,8 @@ TEST_F(AshServiceTest, OpenWindow) {
       aura::CreateInitParamsForTopLevel(client.get(), std::move(properties)));
   window_tree_host_mus.InitHost();
   aura::Window* child_window = new aura::Window(nullptr);
+  child_window->SetProperty(aura::client::kEmbedType,
+                            aura::client::WindowEmbedType::EMBED_IN_OWNER);
   child_window->Init(ui::LAYER_NOT_DRAWN);
   window_tree_host_mus.window()->AddChild(child_window);