Fix clone() behavior on CanvasCaptureMediaStreamTrack

third_party/WebKit/Source/modules/mediacapturefromelement/CanvasCaptureMediaStreamTrack.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 CanvasCaptureMediaStreamTrack_h
 #define CanvasCaptureMediaStreamTrack_h
 
 #include "core/html/canvas/CanvasDrawListener.h"
 #include "modules/mediastream/MediaStreamTrack.h"
 #include "platform/heap/Handle.h"
 
 namespace blink {
 
 class HTMLCanvasElement;
 class WebCanvasCaptureHandler;
 
 class CanvasCaptureMediaStreamTrack final : public MediaStreamTrack {
     DEFINE_WRAPPERTYPEINFO();
 
 public:
     static CanvasCaptureMediaStreamTrack* create(MediaStreamComponent*, PassRefPtrWillBeRawPtr<HTMLCanvasElement>, const PassOwnPtr<WebCanvasCaptureHandler>);
-    DECLARE_VIRTUAL_TRACE();
+
     HTMLCanvasElement* canvas() const;
     void requestFrame();
 
+    CanvasCaptureMediaStreamTrack* clone(ExecutionContext*) override;
+
+    DECLARE_VIRTUAL_TRACE();
+
 private:
+    CanvasCaptureMediaStreamTrack(const CanvasCaptureMediaStreamTrack&, MediaStreamComponent*);
     CanvasCaptureMediaStreamTrack(MediaStreamComponent*, PassRefPtrWillBeRawPtr<HTMLCanvasElement>, const PassOwnPtr<WebCanvasCaptureHandler>);
 
     RefPtrWillBeMember<HTMLCanvasElement> m_canvasElement;
     Member<CanvasDrawListener> m_drawListener;
 };
 
 } // namespace blink
 
 #endif