Remove last uses of InterfaceImpl<> in Sky C++ code

sky/tools/tester/test_runner.h

 // 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.
 
 #ifndef SKY_TOOLS_TESTER_TEST_RUNNER_H_
 #define SKY_TOOLS_TESTER_TEST_RUNNER_H_
 
 #include "base/memory/weak_ptr.h"
 #include "mojo/public/cpp/application/service_provider_impl.h"
 #include "sky/tools/tester/test_harness_impl.h"
 
 namespace mojo{
 class View;
 }
 
 namespace sky {
 namespace tester {
 
 class TestRunnerClient {
  public:
   virtual void OnTestComplete() = 0;
   virtual void DispatchInputEvent(mojo::EventPtr event) = 0;
 
  protected:
   virtual ~TestRunnerClient();
 };
 
-class TestRunner {
+class TestRunner : public mojo::InterfaceFactory<TestHarness> {
  public:
   TestRunner(TestRunnerClient* client, mojo::View* container,
       const std::string& url, bool enable_pixel_dumping);
-  virtual ~TestRunner();
+  ~TestRunner() override;
 
   TestRunnerClient* client() const { return client_; }
-  TestHarnessFactory* test_harness_factory() { return &test_harness_factory_; }
 
   base::WeakPtr<TestRunner> GetWeakPtr();
   void OnTestStart();
   void OnTestComplete(const std::string& test_result,
     const mojo::Array<uint8_t>& pixels);
 
  private:
-  TestHarnessFactory test_harness_factory_;
+  // mojo::InterfaceFactory<TestHarness> implementation:
+  void Create(mojo::ApplicationConnection* app,
+              mojo::InterfaceRequest<TestHarness> request) override;
+
   mojo::ServiceProviderImpl test_harness_provider_impl_;
   TestRunnerClient* client_;
   base::WeakPtrFactory<TestRunner> weak_ptr_factory_;
   bool enable_pixel_dumping_;
 
   MOJO_DISALLOW_COPY_AND_ASSIGN(TestRunner);
 };
 
 }  // namespace tester
 }  // namespace sky
 
 #endif  // SKY_TOOLS_TESTER_TEST_RUNNER_H_