Record UMA stats for Blink decoded image types

Source/platform/image-decoders/webp/WEBPImageDecoder.h

 /*
  * Copyright (C) 2010 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 35 matching lines @@
     String filenameExtension() const override { return "webp"; }
     bool hasColorProfile() const override { return m_hasColorProfile; }
     void setData(SharedBuffer* data, bool allDataReceived) override;
     int repetitionCount() const override;
     bool frameIsCompleteAtIndex(size_t) const override;
     float frameDurationAtIndex(size_t) const override;
     size_t clearCacheExceptFrame(size_t) override;
 
 private:
     // ImageDecoder:
-    virtual void decodeSize() { updateDemuxer(); }
+    void decodeSize() override
+    {
+        updateDemuxer();
+        reportStats(ImageWebP);
+    }
     size_t decodeFrameCount() override;
     void initializeNewFrame(size_t) override;
     void decode(size_t) override;
 
     bool decodeSingleFrame(const uint8_t* dataBytes, size_t dataSize, size_t frameIndex);
 
     WebPIDecoder* m_decoder;
     WebPDecBuffer m_decoderBuffer;
     int m_formatFlags;
     bool m_frameBackgroundHasAlpha;
@@ skipping 22 matching lines @@
     typedef void (*AlphaBlendFunction)(ImageFrame&, ImageFrame&, int, int, int);
     AlphaBlendFunction m_blendFunction;
 
     void clear();
     void clearDecoder();
 };
 
 } // namespace blink
 
 #endif