Record UMA stats for Blink decoded image types

Source/platform/graphics/BitmapImage.cpp

 /*
  * Copyright (C) 2006 Samuel Weinig (sam.weinig@gmail.com)
  * Copyright (C) 2004, 2005, 2006, 2008 Apple 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 315 matching lines @@
     if (!m_haveFrameCount) {
         m_frameCount = m_source.frameCount();
         // If decoder is not initialized yet, m_source.frameCount() returns 0.
         if (m_frameCount)
             m_haveFrameCount = true;
     }
 
     return m_frameCount;
 }
 
+enum DecodedImageType {
+    // These values are histogrammed over time; do not change their ordinal
+    // values.  When deleting an image type, replace it with a dummy value;
+    // when adding an image type, do so at the bottom (and update LastDecodedImageType
+    // so that it equals the last real image type).
+    // Also, this enum should be in sync with the 'DecodedImageType' enum in
+    // src/tools/metrics/histograms/histograms.xml
+    ImageUnknown = 0,
+    ImageJPEG,
+    ImagePNG,
+    ImageGIF,
+    ImageWebP,
+    ImageICO,
+    ImageBMP,
+
+    LastDecodedImageType = ImageBMP
+};
+
+static inline bool hasVisibleImageSize(IntSize size)
+{
+    return (size.width() > 1 || size.height() > 1);
+}
+
 bool BitmapImage::isSizeAvailable()
 {
     if (m_sizeAvailable)
         return true;
 
     m_sizeAvailable = m_source.isSizeAvailable();
 
+    if (m_sizeAvailable && hasVisibleImageSize(size())) {
+        String fileExtention = m_source.filenameExtension();
+        DecodedImageType type =
+            fileExtention == "jpg"  ? ImageJPEG :
+            fileExtention == "png"  ? ImagePNG :
+            fileExtention == "gif"  ? ImageGIF :
+            fileExtention == "webp" ? ImageWebP :
+            fileExtention == "ico"  ? ImageICO :
+            fileExtention == "bmp"  ? ImageBMP :
+            ImageUnknown;
+        Platform::current()->histogramEnumeration("Blink.DecodedImageType", type, LastDecodedImageType + 1);
+    }
+
     return m_sizeAvailable;
 }
 
 bool BitmapImage::ensureFrameIsCached(size_t index)
 {
     if (index >= frameCount())
         return false;
 
     if (index >= m_frames.size() || !m_frames[index].m_frame)
         cacheFrame(index);
@@ skipping 290 matching lines @@
     destroyDecodedDataIfNecessary();
 
     // We need to draw this frame if we advanced to it while not skipping, or if
     // while trying to skip frames we hit the last frame and thus had to stop.
     if (skippingFrames != advancedAnimation)
         imageObserver()->animationAdvanced(this);
     return advancedAnimation;
 }
 
 } // namespace blink