Add rendering context and rendering 2D context to OffscreenCanvas

third_party/WebKit/Source/modules/offscreencanvas/OffscreenCanvasRenderingContext.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 OffscreenCanvasRenderingContext_h
+#define OffscreenCanvasRenderingContext_h
+
+#include "modules/offscreencanvas/OffscreenCanvas.h"
+
+namespace blink {
+
+class OffscreenCanvasRenderingContext : public GarbageCollectedFinalized<OffscreenCanvasRenderingContext>, public ScriptWrappable {
+    WTF_MAKE_NONCOPYABLE(OffscreenCanvasRenderingContext);
+public:
+    virtual ~OffscreenCanvasRenderingContext() { }
+    enum ContextType {
+        Context2d = 0,
+        ContextWebgl = 1,
+        ContextWebgl2 = 2,
+        ContextTypeCount
+    };
+    static ContextType contextTypeFromId(const String& id);
+
+    OffscreenCanvas* offscreenCanvas() const { return m_offscreenCanvas; }
+    virtual ContextType contextType() const = 0;
+
+    virtual bool is2d() const { return false; }
+
+protected:
+    OffscreenCanvasRenderingContext(OffscreenCanvas*);
+    DECLARE_VIRTUAL_TRACE();
+
+private:
+    Member<OffscreenCanvas> m_offscreenCanvas;
+};
+
+} // namespace blink
+
+#endif // OffscreenCanvasRenderingContext_h