Add rendering context and rendering 2D context to OffscreenCanvas

third_party/WebKit/Source/core/html/canvas/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.
+
+#include "core/CoreExport.h"
+#include "core/html/canvas/OffscreenCanvas.h"
+
+namespace blink {
+
+class CORE_EXPORT OffscreenCanvasRenderingContext : public NoBaseWillBeGarbageCollectedFinalized<OffscreenCanvasRenderingContext>, public ScriptWrappable {

[Justin Novosad, 2016/03/02 15:41:50]

This class should also go in the new 'offscreencanvas' module.

+WTF_MAKE_NONCOPYABLE(OffscreenCanvasRenderingContext);
+USING_FAST_MALLOC_WILL_BE_REMOVED(OffscreenCanvasRenderingContext);
+public:
+    virtual ~OffscreenCanvasRenderingContext() { }
+    enum ContextType {
+        Context2d = 0,
+        ContextWebgl = 1,
+        ContextWebgl2 = 2,
+        ContextImageBitmap = 3,

[Justin Novosad, 2016/03/02 15:41:50]

ImageBitmap context will not be supported with OffscreenCanvas

[xlai (Olivia), 2016/03/03 22:50:06]

Done.

+        ContextTypeCount
+    };
+    static ContextType contextTypeFromId(const String& id);
+
+    OffscreenCanvas* offscreenCanvas() const { return m_offscreenCanvas; }
+    ContextType contextType() const { return m_contextType; }
+
+protected:
+    OffscreenCanvasRenderingContext(OffscreenCanvas*);
+    DECLARE_VIRTUAL_TRACE();
+
+private:
+    Member<OffscreenCanvas> m_offscreenCanvas;
+    ContextType m_contextType;
+};
+
+} // namespace blink