[Experiment] Animated image decoder benchmark tool

Source/platform/image-decoders/ImageDecoder.h

Index: Source/platform/image-decoders/ImageDecoder.h
diff --git a/Source/platform/image-decoders/ImageDecoder.h b/Source/platform/image-decoders/ImageDecoder.h
index 7c537063a0901f6ec71f19fdbd3d0f65f2b4ead4..683df2c307780c18011adc45cf55365e108ec8a4 100644
--- a/Source/platform/image-decoders/ImageDecoder.h
+++ b/Source/platform/image-decoders/ImageDecoder.h
@@ -149,6 +149,12 @@ public:
     // Number of bytes in the decoded frame requested. Return 0 if not yet decoded.
     virtual unsigned frameBytesAtIndex(size_t) const;
 
+    virtual size_t countIndependentFrames() const;
+
+    virtual float countAverageDependentFrames() const;
+
+    virtual size_t countMaxDependentFrames() const;
+
     void setIgnoreGammaAndColorProfile(bool flag) { m_ignoreGammaAndColorProfile = flag; }
     bool ignoresGammaAndColorProfile() const { return m_ignoreGammaAndColorProfile; }