Upgrade SkSpecialImage to have getTextureRef & getROPixels entry points

This more closely aligns the SkSpecialImage API with the SkImage API. In doing so it allows the image filters to handle SkImages that can sneak through while remaining encoded (e.g., if an input filter just returns a wrapped version of the source SkImage)

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Review URL: https://codereview.chromium.org/1861643003
10 files changed