Record UMA stats for Blink decoded image types

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

Index: Source/platform/image-decoders/webp/WEBPImageDecoder.h
diff --git a/Source/platform/image-decoders/webp/WEBPImageDecoder.h b/Source/platform/image-decoders/webp/WEBPImageDecoder.h
index 1c43e559b396b10540a044fed0e704a36f98fe62..8a1e447f57774eecc60ea17af2ee7d32b9d687bf 100644
--- a/Source/platform/image-decoders/webp/WEBPImageDecoder.h
+++ b/Source/platform/image-decoders/webp/WEBPImageDecoder.h
@@ -53,7 +53,11 @@ public:
 
 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;