[Sync] Fixing easy lint violations.

components/sync/core/test/fake_model_type_connector.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 COMPONENTS_SYNC_CORE_TEST_FAKE_MODEL_TYPE_CONNECTOR_H_
 #define COMPONENTS_SYNC_CORE_TEST_FAKE_MODEL_TYPE_CONNECTOR_H_
 
+#include <memory>
+
 #include "components/sync/core/model_type_connector.h"
 
 namespace syncer {
 
 // A no-op implementation of ModelTypeConnector for testing.
 class FakeModelTypeConnector : public ModelTypeConnector {
  public:
   FakeModelTypeConnector();
   ~FakeModelTypeConnector() override;
 
   void ConnectType(
       ModelType type,
       std::unique_ptr<ActivationContext> activation_context) override;
   void DisconnectType(ModelType type) override;
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_SYNC_CORE_TEST_FAKE_MODEL_TYPE_CONNECTOR_H_