Record UMA stats for Blink decoded image types

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

 /*
  * Copyright (C) 2006 Apple Computer, 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
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 49 matching lines @@
     // 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 frameComplete(size_t frameIndex);
 
     // For testing.
     bool parseCompleted() const;
 
 private:
     // ImageDecoder:
     void clearFrameBuffer(size_t frameIndex) override;
-    virtual void decodeSize() { parse(GIFSizeQuery); }
+    virtual void decodeSize()
+    {
+        parse(GIFSizeQuery);
+        reportStats(ImageGIF);
+    }
     size_t decodeFrameCount() override;
     void initializeNewFrame(size_t) override;
     void decode(size_t) override;
 
     // Parses as much as is needed to answer the query, ignoring bitmap
     // data. If parsing fails, sets the "decode failure" flag.
     void parse(GIFParseQuery);
 
     // Called to initialize the frame buffer with the given index, based on
     // 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 m_currentBufferSawAlpha;
     mutable int m_repetitionCount;
     OwnPtr<GIFImageReader> m_reader;
 };
 
 } // namespace blink
 
 #endif