Animated PNG implementation

Source/platform/image-decoders/png/PNGImageDecoder.h

Index: Source/platform/image-decoders/png/PNGImageDecoder.h
diff --git a/Source/platform/image-decoders/png/PNGImageDecoder.h b/Source/platform/image-decoders/png/PNGImageDecoder.h
index 7f54c2e360725981b96c9c96ce4cb6b331a77995..9ed6ebfc93d1d14dcb5b0d1cbed66dc8ffa8b197 100644
--- a/Source/platform/image-decoders/png/PNGImageDecoder.h
+++ b/Source/platform/image-decoders/png/PNGImageDecoder.h
@@ -43,6 +43,10 @@ public:
     // ImageDecoder:
     String filenameExtension() const override { return "png"; }
     bool hasColorProfile() const override { return m_hasColorProfile; }
+    bool frameIsCompleteAtIndex(size_t) const override;
+    float frameDurationAtIndex(size_t) const override;
+    int repetitionCount() const override;
+    size_t clearCacheExceptFrame(size_t) override;
 
     // Callbacks from libpng
     void headerAvailable();
@@ -51,16 +55,17 @@ public:
 
 private:
     // ImageDecoder:
-    void decodeSize() override { decode(true); }
-    void decode(size_t) override { decode(false); }
+    void decodeSize() override { parse(); }
+    void decode(size_t) override;
+    size_t decodeFrameCount() override;
+    void initializeNewFrame(size_t) override;
 
-    // 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);
+    bool initFrameBuffer();
+    bool parse();
 
     OwnPtr<PNGImageReader> m_reader;
     bool m_hasColorProfile;
+    size_t m_currentFrame;
 };
 
 } // namespace blink