Revert "Remove OwnPtr from Blink."

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.h

 // 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.
 
 #ifndef OffscreenCanvasRenderingContext2D_h
 #define OffscreenCanvasRenderingContext2D_h
 
 #include "core/html/canvas/CanvasContextCreationAttributes.h"
 #include "core/html/canvas/CanvasRenderingContext.h"
 #include "core/html/canvas/CanvasRenderingContextFactory.h"
 #include "modules/canvas2d/BaseRenderingContext2D.h"
-#include <memory>
 
 namespace blink {
 
 class MODULES_EXPORT OffscreenCanvasRenderingContext2D final : public CanvasRenderingContext, public BaseRenderingContext2D {
     DEFINE_WRAPPERTYPEINFO();
     USING_GARBAGE_COLLECTED_MIXIN(OffscreenCanvasRenderingContext2D);
 public:
     class Factory : public CanvasRenderingContextFactory {
     public:
         Factory() {}
@@ skipping 51 matching lines @@
 
     ImageBitmap* transferToImageBitmap(ExceptionState&) final;
 
 protected:
     OffscreenCanvasRenderingContext2D(OffscreenCanvas*, const CanvasContextCreationAttributes& attrs);
     DECLARE_VIRTUAL_TRACE();
 
 private:
     bool m_hasAlpha;
     bool m_needsMatrixClipRestore = false;
-    std::unique_ptr<ImageBuffer> m_imageBuffer;
+    OwnPtr<ImageBuffer> m_imageBuffer;
 };
 
 } // namespace blink
 
 #endif // OffscreenCanvasRenderingContext2D_h