GIF decoding to Index8, unit tests and misusing unit test as benchmark

third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h

Index: third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h
diff --git a/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h b/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h
index e37f7a37561d1e61d608720f64a57ef9040747c5..6905a9eb32a050b1adc4f51c9bb1ce1775d770bb 100644
--- a/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h
+++ b/third_party/WebKit/Source/platform/image-decoders/gif/GIFImageDecoder.h
@@ -58,12 +58,26 @@ public:
     bool setFailed() override;
 
     // Callbacks from the GIF reader.
-    bool haveDecodedRow(size_t frameIndex, GIFRow::const_iterator rowBegin, size_t width, size_t rowNumber, unsigned repeatCount, bool writeTransparentPixels);
+    bool (GIFImageDecoder::*phaveDecodedRow)(size_t frameIndex, GIFRow::const_iterator rowBegin, size_t width, size_t rowNumber, unsigned repeatCount, bool writeTransparentPixels);
+    inline bool haveDecodedRow(size_t frameIndex, GIFRow::const_iterator rowBegin, size_t width, size_t rowNumber, unsigned repeatCount, bool writeTransparentPixels)
+    {
+        return (this->*phaveDecodedRow)(frameIndex, rowBegin, width, rowNumber, repeatCount, writeTransparentPixels);
+    }
     bool frameComplete(size_t frameIndex);
 
+    // Callback implementations for different output.
+    bool haveDecodedRowN32(size_t frameIndex, GIFRow::const_iterator rowBegin, size_t width, size_t rowNumber, unsigned repeatCount, bool writeTransparentPixels);
+    bool haveDecodedRowIndex8(size_t frameIndex, GIFRow::const_iterator rowBegin, size_t width, size_t rowNumber, unsigned repeatCount, bool writeTransparentPixels);
+
+    // Callback when reader detects state requiring RGBA decoding.
+    void setForceN32Decoding(bool);
+
     // For testing.
     bool parseCompleted() const;
 
+    // For supporting both N32 and Index8 output.
+    bool canDecodeTo(size_t index, ImageFrame::ColorType outputType) override;
+
 private:
     // ImageDecoder:
     void clearFrameBuffer(size_t frameIndex) override;
@@ -71,6 +85,8 @@ private:
     size_t decodeFrameCount() override;
     void initializeNewFrame(size_t) override;
     void decode(size_t) override;
+    void decodeTo(size_t index, ImageFrame::ColorType outputColor) override;
+
 
     // Parses as much as is needed to answer the query, ignoring bitmap
     // data. If parsing fails, sets the "decode failure" flag.
@@ -80,10 +96,18 @@ private:
     // the previous frame's disposal method. Returns true on success. On
     // failure, this will mark the image as failed.
     bool initFrameBuffer(size_t frameIndex);
+    bool initFrameBufferIndex8(size_t frameIndex);
 
     bool m_currentBufferSawAlpha;
     mutable int m_repetitionCount;
     OwnPtr<GIFImageReader> m_reader;
+
+    // Holds information about which decoding output was in client request.
+    ImageFrame::ColorType m_colorMode;
+
+    // In Index8 decoding mode, some of the frames need to get decoded to N32.
+    // This flag is reset when situation allows going back to Index8 decoding in initFrameBuffer.
+    bool m_forceN32Decoding;
 };
 
 } // namespace blink