Update libpng to 1.6.22

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

 /*
  * Copyright (C) 2006 Apple Computer, Inc.
  * Copyright (C) Research In Motion Limited 2009-2010. All rights reserved.
  *
  * Portions are Copyright (C) 2001 mozilla.org
  *
  * Other contributors:
  *   Stuart Parmenter <stuart@mozilla.com>
  *
  * This library is free software; you can redistribute it and/or
@@ skipping 166 matching lines @@
 void PNGImageDecoder::headerAvailable()
 {
     png_structp png = m_reader->pngPtr();
     png_infop info = m_reader->infoPtr();
     png_uint_32 width = png_get_image_width(png, info);
     png_uint_32 height = png_get_image_height(png, info);
 
     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;
     if (width > maxPNGSize || height > maxPNGSize) {
         longjmp(JMPBUF(png), 1);
         return;
     }
 
     // Set the image size now that the image header is available.
     if (!setSize(width, height)) {
@@ skipping 31 matching lines @@
         // do not similarly transform the color profile. We'd either need to transform
         // the color profile or we'd need to decode into a gray-scale image buffer and
         // hand that to CoreGraphics.
         bool imageHasAlpha = (colorType & PNG_COLOR_MASK_ALPHA) || trnsCount;
 #ifdef PNG_iCCP_SUPPORTED
         if (png_get_valid(png, info, PNG_INFO_sRGB)) {
             setColorProfileAndTransform(nullptr, 0, imageHasAlpha, true /* useSRGB */);
         } else {
             char* profileName = nullptr;
             int compressionType = 0;
 #if (PNG_LIBPNG_VER < 10500)

[Nico, 2016/06/03 20:27:44]

looks like you can tweak this instead of casting?

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

png_get_iCCP needs profile to be an unsigned char* and
setColorProfileAndTransform needs it to be a char*.  I think we need a cast
somewhere.

[Nico, 2016/06/03 21:36:49]

Hm, the other caller of setColorProfileAndTransform() also casts:
https://cs.chromium.org/chromium/src/third_party/WebKit/Source/platform/image...

If each caller wants to pass an unsigned char*, maybe we should change
setColorProfileAndTransform() to take that ... but looking a bit, that compares
the data to string literals, so those would then need a cast instead. Ok, but
please use a c++-style reinterpret_cast then.

[msarett, 2016/06/06 14:18:15]

Done.

             png_charp profile = nullptr;
 #else
             png_bytep profile = nullptr;
 #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
     }
 #endif // USE(QCMSLIB)
 
     if (!hasColorProfile()) {
         // Deal with gamma and keep it under our control.
         const double inverseGamma = 0.45455;
         const double defaultGamma = 2.2;
@@ skipping 184 matching lines @@
     // has failed.
     if (!m_reader->decode(*m_data, onlySize) && isAllDataReceived())
         setFailed();
 
     // If decoding is done or failed, we don't need the PNGImageReader anymore.
     if (isComplete(this) || failed())
         m_reader.reset();
 }
 
 } // namespace blink