Revert "Remove OwnPtr from Blink."

third_party/WebKit/Source/core/editing/EditingTestBase.h

 // Copyright 2015 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 EditingTestBase_h
 #define EditingTestBase_h
 
 #include "core/editing/Position.h"
 #include "wtf/Forward.h"
 #include <gtest/gtest.h>
-#include <memory>
 #include <string>
 
 namespace blink {
 
 class DummyPageHolder;
 
 class EditingTestBase : public ::testing::Test {
     USING_FAST_MALLOC(EditingTestBase);
 protected:
     EditingTestBase();
     ~EditingTestBase() override;
 
     void SetUp() override;
 
     Document& document() const;
     DummyPageHolder& dummyPageHolder() const { return *m_dummyPageHolder; }
 
     static ShadowRoot* createShadowRootForElementWithIDAndSetInnerHTML(TreeScope&, const char* hostElementID, const char* shadowRootContent);
 
     void setBodyContent(const std::string&);
     ShadowRoot* setShadowContent(const char* shadowContent, const char* shadowHostId);
     void updateAllLifecyclePhases();
 
 private:
-    std::unique_ptr<DummyPageHolder> m_dummyPageHolder;
+    OwnPtr<DummyPageHolder> m_dummyPageHolder;
 };
 
 } // namespace blink
 
 #endif // EditingTestBase_h