[HTMLCanvasElement.toBlob] Default callback version without scheduler

Source/core/html/HTMLCanvasElement.h

 /*
  * Copyright (C) 2004, 2006, 2009, 2010 Apple Inc. All rights reserved.
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. 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.
@@ skipping 15 matching lines @@
  */
 
 #ifndef HTMLCanvasElement_h
 #define HTMLCanvasElement_h
 
 #include "bindings/core/v8/ScriptValue.h"
 #include "bindings/core/v8/UnionTypesCore.h"
 #include "core/CoreExport.h"
 #include "core/dom/Document.h"
 #include "core/dom/DocumentVisibilityObserver.h"
+#include "core/fileapi/FileCallback.h"
 #include "core/html/HTMLElement.h"
 #include "core/html/canvas/CanvasImageSource.h"
 #include "platform/geometry/FloatRect.h"
 #include "platform/geometry/IntSize.h"
 #include "platform/graphics/GraphicsTypes.h"
 #include "platform/graphics/GraphicsTypes3D.h"
 #include "platform/graphics/ImageBufferClient.h"
 #include "platform/heap/Handle.h"
 
 #define CanvasDefaultInterpolationQuality InterpolationLow
@@ skipping 60 matching lines @@
     ScriptValue getContext(ScriptState*, const String&, const CanvasContextCreationAttributes&);
     // Called by Document::getCSSCanvasContext as well as above getContext().
     CanvasRenderingContext* getCanvasRenderingContext(const String&, const CanvasContextCreationAttributes&);
 
     bool isPaintable() const;
 
     static String toEncodingMimeType(const String& mimeType);
     String toDataURL(const String& mimeType, const ScriptValue& qualityArgument, ExceptionState&) const;
     String toDataURL(const String& mimeType, ExceptionState& exceptionState) const { return toDataURL(mimeType, ScriptValue(), exceptionState); }
 
+    void toBlob(FileCallback*, const String& mimeType, const ScriptValue& qualityArgument, ExceptionState&) const;
+    void toBlob(FileCallback* callback, const String& mimeType, ExceptionState& exceptionState) { return toBlob(callback, mimeType, ScriptValue(), exceptionState); }

[Noel Gordon, 2015/08/28 08:53:47]

nit: if you removed this line, does chrome compile?  Not sure there are any
callers of this second variant of toBlob (or the similar toDataURL variant
either). We should remove them if they are dead-code.

[xlai (Olivia), 2015/08/28 19:54:19]

Haven't tried removing it and compile yet; I'll give a try later. 

But I don't think they are dead code. What if users call toBlob or toDataURL
functions without supplying any quality arguments? 

+
     // Used for rendering
     void didDraw(const FloatRect&);
     void notifyObserversCanvasChanged(const FloatRect&);
 
     void paint(GraphicsContext*, const LayoutRect&);
 
     SkCanvas* drawingCanvas() const;
     void disableDeferral() const;
     SkCanvas* existingDrawingCanvas() const;
 
@@ skipping 100 matching lines @@
     mutable bool m_didFailToCreateImageBuffer;
     bool m_imageBufferIsClear;
     OwnPtr<ImageBuffer> m_imageBuffer;
 
     mutable RefPtr<Image> m_copiedImage; // FIXME: This is temporary for platforms that have to copy the image buffer to render (and for CSSCanvasValue).
 };
 
 } // namespace blink
 
 #endif // HTMLCanvasElement_h