DeferredImageDecoder: early-out onGetYUV8Planes when possible

third_party/WebKit/Source/platform/graphics/DecodingImageGenerator.h

 /*
  * Copyright (C) 2013 Google 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
@@ skipping 28 matching lines @@
 
 class ImageFrameGenerator;
 
 // Implements SkImageGenerator, used by SkPixelRef to populate a discardable memory
 // with a decoded image frame. ImageFrameGenerator does the actual decoding.
 //
 class PLATFORM_EXPORT DecodingImageGenerator final : public SkImageGenerator {
     USING_FAST_MALLOC(DecodingImageGenerator);
     WTF_MAKE_NONCOPYABLE(DecodingImageGenerator);
 public:
-    static SkImageGenerator* create(SkData*);
-
     DecodingImageGenerator(PassRefPtr<ImageFrameGenerator>, const SkImageInfo&, size_t index);
     ~DecodingImageGenerator() override;
 
     void setGenerationId(size_t id) { m_generationId = id; }
+    void setCanYUVDecode(bool yes) { m_canYUVDecode = yes; }
+
+    static SkImageGenerator* create(SkData*); // Highly unsual access.

[scroggo_chromium, 2015/12/07 16:40:02]

unusual*

Is the goal of this comment to say something like "do not use unless you know
what you're doing?". "Highly unusual access" just seems like a description
(which may cease to be true, unless we enforce it through code review).

Should we discourage using it though? Is there a problem with it?

[Noel Gordon, 2015/12/08 01:40:08]

The goal was just to point it out, to you, since it might have implications for
your work.
I'm not really sure why this API exists, but if you follow the code paths you
might find out why, and whether it has any implications for your work.

Done pointing it out, so I will remove this part of the change, to make git
blame easier for later investigations about the purpose of the unusual API.

 
 protected:
     SkData* onRefEncodedData() override;
 
     bool onGetPixels(const SkImageInfo&, void* pixels, size_t rowBytes, SkPMColor table[], int* tableCount) override;
 
     bool onGetYUV8Planes(SkISize sizes[3], void* planes[3], size_t rowBytes[3], SkYUVColorSpace*) override;
 
 private:
     RefPtr<ImageFrameGenerator> m_frameGenerator;
     size_t m_frameIndex;
     size_t m_generationId;
+    bool m_canYUVDecode;
 };
 
 } // namespace blink
 
 #endif // DecodingImageGenerator_h_