Update libpng to 1.6.22

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

Index: third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
diff --git a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
index d444caa0bf644e481d7a9f15e3952de5ec2c4397..151cded10509ff3f6e45b70a1aac8111ac2b9aec 100644
--- a/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
+++ b/third_party/WebKit/Source/platform/image-decoders/png/PNGImageDecoder.cpp
@@ -184,7 +184,7 @@ void PNGImageDecoder::headerAvailable()
     DEFINE_THREAD_SAFE_STATIC_LOCAL(blink::CustomCountHistogram,
         dimensionsLocationHistogram,
         new blink::CustomCountHistogram("Blink.DecodedImage.EffectiveDimensionsLocation.PNG", 0, 50000, 50));
-    dimensionsLocationHistogram.count(m_reader->getReadOffset() - png->current_buffer_size - 1);

[msarett, 2016/06/03 20:18:51]

@ryansturm

libpng 1.6 has a stricter API that does not allow direct access to the
png_structp.  I'm not aware that there is a way to get this information anymore.
 What is the impact of this metric overestimating a little bit?

[RyanSturm, 2016/06/03 20:31:51]

You can remove the Blink.DecodedImage.EffectiveDimensionsLocation.PNG histogram.
We have enough data from canary/dev, and don't expect much to change.

[msarett, 2016/06/03 21:26:01]

Got it thanks!  It's been removed.

[scroggo_chromium, 2016/06/06 14:51:40]

I suppose it's safe to remove the rest of them, too? (In a separate change.)

+    dimensionsLocationHistogram.count(m_reader->getReadOffset() - 1);
 
     // Protect against large PNGs. See http://bugzil.la/251381 for more details.
     const unsigned long maxPNGSize = 1000000UL;
@@ -243,7 +243,7 @@ void PNGImageDecoder::headerAvailable()
 #endif
             png_uint_32 profileLength = 0;
             if (png_get_iCCP(png, info, &profileName, &compressionType, &profile, &profileLength)) {
-                setColorProfileAndTransform(profile, profileLength, imageHasAlpha, false /* useSRGB */);
+                setColorProfileAndTransform((char*) profile, profileLength, imageHasAlpha, false /* useSRGB */);
             }
         }
 #endif // PNG_iCCP_SUPPORTED