Add rendering context and rendering 2D context to OffscreenCanvas

third_party/WebKit/Source/modules/canvas2d/OffscreenCanvasRenderingContext2D.h

Index: third_party/WebKit/Source/modules/canvas2d/OffscreenCanvasRenderingContext2D.h
diff --git a/third_party/WebKit/Source/modules/canvas2d/OffscreenCanvasRenderingContext2D.h b/third_party/WebKit/Source/modules/canvas2d/OffscreenCanvasRenderingContext2D.h
new file mode 100644
index 0000000000000000000000000000000000000000..6cd339399760f8e2052302852564dd1085e0d808
--- /dev/null
+++ b/third_party/WebKit/Source/modules/canvas2d/OffscreenCanvasRenderingContext2D.h
@@ -0,0 +1,75 @@
+// 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/html/canvas/CanvasContextCreationAttributes.h"
+#include "core/html/canvas/OffscreenCanvasRenderingContext.h"
+#include "core/html/canvas/OffscreenCanvasRenderingContextFactory.h"
+#include "modules/canvas2d/BaseRenderingContext2D.h"
+
+namespace blink {
+
+class OffscreenCanvasRenderingContext2D final : public OffscreenCanvasRenderingContext, public BaseRenderingContext2D {

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

This should go into yet another module 'offscreencanvas2d'

+    DEFINE_WRAPPERTYPEINFO();
+    WILL_BE_USING_GARBAGE_COLLECTED_MIXIN(OffscreenCanvasRenderingContext2D);
+public:
+    class Factory : public OffscreenCanvasRenderingContextFactory {
+        WTF_MAKE_NONCOPYABLE(Factory);
+
+    public:
+        Factory() {}
+        ~Factory() override {}
+
+        PassOwnPtrWillBeRawPtr<OffscreenCanvasRenderingContext> create(OffscreenCanvas* canvas, const CanvasContextCreationAttributes& attrs) override
+        {
+            return adoptPtrWillBeNoop(new OffscreenCanvasRenderingContext2D(canvas, attrs));
+        }
+
+        OffscreenCanvasRenderingContext::ContextType contextType() const override
+        {
+            return OffscreenCanvasRenderingContext::Context2d;
+        }
+
+        void onError(OffscreenCanvas* canvas, const String& error) override {}
+    };
+
+    ~OffscreenCanvasRenderingContext2D() override;
+
+    // BaseRenderingContext2D implementation
+    bool originClean() const final;

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

For a future CL, stuff that is shared between OCRC2D and CRC2D should be pushed
up into BaseRenderingContext2D so that we don't have to implement twice.  Ian K
made this stuff virtual because it is not needed for Houdini, but some of these
choices need to be re-visited.  I some cases, we could keep the methods virtual
and to stub them out in PRC2D, but, still have a shared implementation in BRC2D.

+    void setOriginTainted() final;
+    bool wouldTaintOrigin(CanvasImageSource*) final;
+
+    int width() const final;
+    int height() const final;
+
+    bool hasImageBuffer() const final;
+    ImageBuffer* imageBuffer() const final;
+
+    bool parseColorOrCurrentColor(Color&, const String& colorString) const final;
+
+    SkCanvas* drawingCanvas() const final;
+    SkCanvas* existingDrawingCanvas() const final;
+    void disableDeferral(DisableDeferralReason) final;
+
+    AffineTransform baseTransform() const final;
+    void didDraw(const SkIRect& dirtyRect) final;
+
+    bool stateHasFilter() final;
+    SkImageFilter* stateGetFilter() final;
+
+    void validateStateStack() final;
+
+    bool hasAlpha() const override { return m_hasAlpha; }
+    bool isContextLost() const override;
+
+protected:
+    OffscreenCanvasRenderingContext2D(OffscreenCanvas*, const CanvasContextCreationAttributes& attrs);
+    DECLARE_VIRTUAL_TRACE();
+
+private:
+    bool m_hasAlpha;
+};
+
+} // namespace blink
+