Use a union typdef for the return type of canvas.getContext

third_party/WebKit/Source/modules/canvas2d/CanvasRenderingContext2D.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 65 matching lines @@
         PassOwnPtrWillBeRawPtr<CanvasRenderingContext> create(HTMLCanvasElement* canvas, const CanvasContextCreationAttributes& attrs, Document& document) override
         {
             return adoptPtrWillBeNoop(new CanvasRenderingContext2D(canvas, attrs, document));
         }
         CanvasRenderingContext::ContextType getContextType() const override { return CanvasRenderingContext::Context2d; }
         void onError(HTMLCanvasElement*, const String& error) override { }
     };
 
     ~CanvasRenderingContext2D() override;
 
+    void setCanvasGetContextResult(RenderingContext&) final;

[sof, 2016/03/09 22:05:26]

"final" on a "final" class - i'm (honestly) unfamiliar with that idiom - what
are trying to state?

[Justin Novosad, 2016/03/09 22:31:00]

Since the class is "final" there is no technical difference between using
"final" or "override" here. I looked at the style guide section on C++11
features used in Chromium and there is no specific guidance on which is
preferred on a class that is "final".

+
     bool isContextLost() const override;
 
     void setShouldAntialias(bool) override;
 
     void scrollPathIntoView();
     void scrollPathIntoView(Path2D*);
 
     void clearRect(double x, double y, double width, double height) override;
 
     void reset() override;
@@ skipping 118 matching lines @@
     HashMap<String, Font> m_fontsResolvedUsingCurrentStyle;
     bool m_pruneLocalFontCacheScheduled;
     ListHashSet<String> m_fontLRUList;
 };
 
 DEFINE_TYPE_CASTS(CanvasRenderingContext2D, CanvasRenderingContext, context, context->is2d(), context.is2d());
 
 } // namespace blink
 
 #endif // CanvasRenderingContext2D_h