Fix GPU service and display initialization race.

services/ui/ws/test_utils.h

 // 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.
 
 #ifndef SERVICES_UI_WS_TEST_UTILS_H_
 #define SERVICES_UI_WS_TEST_UTILS_H_
 
 #include <stdint.h>
 
 #include <memory>
@@ skipping 504 matching lines @@
   std::vector<TestWindowTreeBinding*>* bindings() { return &bindings_; }
 
   bool got_on_no_more_displays() const { return got_on_no_more_displays_; }
 
   // Creates |num_displays| displays.
   void CreateDisplays(int num_displays);
 
   Display* AddDisplay();
 
   // WindowServerDelegate:
+  void StartDisplayInit() override;
   void OnNoMoreDisplays() override;
   std::unique_ptr<WindowTreeBinding> CreateWindowTreeBinding(
       BindingType type,
       ws::WindowServer* window_server,
       ws::WindowTree* tree,
       mojom::WindowTreeRequest* tree_request,
       mojom::WindowTreeClientPtr* client) override;
   bool IsTestConfig() const override;
   void UpdateTouchTransforms() override {}
 
@@ skipping 107 matching lines @@
 ServerWindow* NewWindowInTree(WindowTree* tree, ClientWindowId* client_id);
 ServerWindow* NewWindowInTreeWithParent(WindowTree* tree,
                                         ServerWindow* parent,
                                         ClientWindowId* client_id);
 
 }  // namespace test
 }  // namespace ws
 }  // namespace ui
 
 #endif  // SERVICES_UI_WS_TEST_UTILS_H_