Make OffscreenCanvas a member of CanvasImageSource

third_party/WebKit/Source/modules/offscreencanvas2d/OffscreenCanvasRenderingContext2D.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 OffscreenCanvasRenderingContext2D_h
 #define OffscreenCanvasRenderingContext2D_h
 
 #include "core/html/canvas/CanvasContextCreationAttributes.h"
 #include "core/html/canvas/CanvasRenderingContext.h"
 #include "core/html/canvas/CanvasRenderingContextFactory.h"
@@ skipping 24 matching lines @@
 
     // CanvasRenderingContext implementation
     ~OffscreenCanvasRenderingContext2D() override;
     ContextType getContextType() const override { return Context2d; }
     bool is2d() const override { return true; }
     void setOffscreenCanvasGetContextResult(OffscreenRenderingContext&) final;
     void setIsHidden(bool) final { ASSERT_NOT_REACHED(); }
     void stop() final { ASSERT_NOT_REACHED(); }
     void setCanvasGetContextResult(RenderingContext&) final {}
     void clearRect(double x, double y, double width, double height) override { BaseRenderingContext2D::clearRect(x, y, width, height); }
+    PassRefPtr<Image> getImage(SnapshotReason) const final;
 
     // BaseRenderingContext2D implementation
     bool originClean() const final;
     void setOriginTainted() final;
     bool wouldTaintOrigin(CanvasImageSource*, ExecutionContext*) final;
 
     int width() const final;
     int height() const final;
 
     bool hasImageBuffer() const final;
@@ skipping 30 matching lines @@
     bool isPaintable() const final;
 };
 
 DEFINE_TYPE_CASTS(OffscreenCanvasRenderingContext2D, CanvasRenderingContext, context,
     context->is2d() && context->getOffscreenCanvas(),
     context.is2d() && context.getOffscreenCanvas());
 
 } // namespace blink
 
 #endif // OffscreenCanvasRenderingContext2D_h