Allowing YUV data to be retrieved from the JPEG Decoder.

Source/platform/image-decoders/jpeg/JPEGImageDecoder.h

 /*
  * Copyright (C) 2006 Apple Computer, Inc.  All rights reserved.
  * Copyright (C) 2008-2009 Torch Mobile, Inc.
  *
  * 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
@@ skipping 30 matching lines @@
     WTF_MAKE_NONCOPYABLE(JPEGImageDecoder);
 public:
     JPEGImageDecoder(ImageSource::AlphaOption, ImageSource::GammaAndColorProfileOption, size_t maxDecodedBytes);
     virtual ~JPEGImageDecoder();
 
     // ImageDecoder
     virtual String filenameExtension() const OVERRIDE { return "jpg"; }
     virtual bool isSizeAvailable() OVERRIDE;
     virtual bool hasColorProfile() const OVERRIDE { return m_hasColorProfile; }
     virtual IntSize decodedSize() const OVERRIDE { return m_decodedSize; }
+    virtual IntSize decodedYUVSize(int component) const OVERRIDE;
     virtual bool setSize(unsigned width, unsigned height) OVERRIDE;
     virtual ImageFrame* frameBufferAtIndex(size_t) OVERRIDE;
     // CAUTION: setFailed() deletes |m_reader|.  Be careful to avoid
     // accessing deleted memory, especially when calling this from inside
     // JPEGImageReader!
     virtual bool setFailed() OVERRIDE;
+    virtual bool YUVDecoding() const OVERRIDE { return m_imagePlanes.get(); }

[Noel Gordon, 2014/07/28 07:29:07]

Could you have imagePlanes, but be decoding into output_color_space RGBA?

+    virtual bool decodeToYUV() OVERRIDE;
+    virtual void setImagePlanes(OwnPtr<ImagePlanes>&) OVERRIDE;
 
     bool outputScanlines();
     unsigned desiredScaleNumerator() const;
     void jpegComplete();
 
     void setOrientation(ImageOrientation orientation) { m_orientation = orientation; }
     void setHasColorProfile(bool hasColorProfile) { m_hasColorProfile = hasColorProfile; }
     void setDecodedSize(unsigned width, unsigned height);
 
 private:
     // Decodes the image.  If |onlySize| is true, stops decoding after
     // calculating the image size.  If decoding fails but there is no more
     // data coming, sets the "decode failure" flag.
     void decode(bool onlySize);
 
     OwnPtr<JPEGImageReader> m_reader;
+    OwnPtr<ImagePlanes> m_imagePlanes;
     IntSize m_decodedSize;
     bool m_hasColorProfile;
 };
 
 } // namespace blink
 
 #endif