Add metrics for how often APNGs are used

third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.cpp

Index: third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.cpp b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.cpp
index ccfd5fcd211ba2571fc51718cd0fef3552fc1dc9..6291f6ff4a3fb2882ac132bd5b7d6fc6ddae756d 100644
--- a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageReader.cpp
@@ -39,6 +39,7 @@
 #include "platform/image-decoders/png/PNGImageReader.h"
 
 #include <memory>
+#include "platform/Histogram.h"
 #include "platform/image-decoders/FastSharedBufferReader.h"
 #include "platform/image-decoders/SegmentReader.h"
 #include "platform/image-decoders/png/PNGImageDecoder.h"
@@ -535,6 +536,12 @@ bool PNGImageReader::parseSize(const FastSharedBufferReader& reader) {
       if (!m_isAnimated || 1 == m_reportedFrameCount)
         m_decoder->setRepetitionCount(cAnimationNone);
       m_decoder->headerAvailable();
+      {
+        DEFINE_THREAD_SAFE_STATIC_LOCAL(
+            BooleanHistogram, apngHistogram,
+            new BooleanHistogram("Blink.DecodedImage.APNG"));
+        apngHistogram.count(m_isAnimated);
+      }
       return true;
     }