Add rendering context and rendering 2D context to OffscreenCanvas

third_party/WebKit/Source/core/html/canvas/OffscreenCanvas.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 OffscreenCanvas_h
-#define OffscreenCanvas_h
-
-#include "bindings/core/v8/ScriptPromise.h"
-#include "bindings/core/v8/ScriptState.h"
-#include "bindings/core/v8/ScriptWrappable.h"
-#include "core/CoreExport.h"
-#include "platform/geometry/IntSize.h"
-#include "platform/heap/Handle.h"
-
-namespace blink {
-
-class CORE_EXPORT OffscreenCanvas final : public GarbageCollectedFinalized<OffscreenCanvas>, public ScriptWrappable {
-    DEFINE_WRAPPERTYPEINFO();
-public:
-    static OffscreenCanvas* create(unsigned width, unsigned height);
-
-    IntSize size() const { return m_size; }
-    unsigned width() const { return m_size.width(); }
-    unsigned height() const { return m_size.height(); }
-
-    void setWidth(unsigned);
-    void setHeight(unsigned);
-
-    DECLARE_VIRTUAL_TRACE();
-
-private:
-    OffscreenCanvas(const IntSize&);
-
-    IntSize m_size;
-};
-
-} // namespace blink
-
-#endif // OffscreenCanvas_h