Convert mustash use surface references.

services/ui/ws/test_utils.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 "services/ui/ws/test_utils.h"
 
 #include <utility>
 
 #include "base/memory/ptr_util.h"
 #include "cc/output/copy_output_request.h"
@@ skipping 47 matching lines @@
     if (display_metrics_ == metrics)
       return false;
     display_metrics_ = metrics;
     return true;
   }
   const display::ViewportMetrics& GetViewportMetrics() const override {
     return display_metrics_;
   }
   void OnGpuChannelEstablished(
       scoped_refptr<gpu::GpuChannelHost> host) override {}
+  FrameGenerator* GetFrameGenerator() override { return nullptr; }
 
  private:
   const int64_t id_;
   display::ViewportMetrics display_metrics_;
   mojom::Cursor* cursor_storage_;
 
   DISALLOW_COPY_AND_ASSIGN(TestPlatformDisplay);
 };
 
 ClientWindowId NextUnusedClientWindowId(WindowTree* tree) {
@@ skipping 546 matching lines @@
     return nullptr;
   if (!tree->AddWindow(parent_client_id, client_window_id))
     return nullptr;
   *client_id = client_window_id;
   return tree->GetWindowByClientId(client_window_id);
 }
 
 }  // namespace test
 }  // namespace ws
 }  // namespace ui