[Ozone-DRI] Removing MockDriSurface implementation

ui/ozone/platform/dri/test/mock_surface_generator.cc

 // Copyright 2014 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 "ui/ozone/platform/dri/test/mock_surface_generator.h"
 
 namespace ui {
 
 MockSurfaceGenerator::MockSurfaceGenerator(DriWrapper* dri) : dri_(dri) {}
 
 MockSurfaceGenerator::~MockSurfaceGenerator() {}
 
 ScanoutSurface* MockSurfaceGenerator::Create(const gfx::Size& size) {
-  surfaces_.push_back(new MockDriSurface(dri_, size));
+  surfaces_.push_back(new DriSurface(dri_, size));
   return surfaces_.back();
 }
 
 }  // namespace ui