Code: png_get_copyright(png_structp png_ptr)
{
   PNG_UNUSED(png_ptr)  /* Silence compiler warning about unused png_ptr */
#ifdef PNG_STRING_COPYRIGHT
      return PNG_STRING_COPYRIGHT
 #else
 #ifdef __STDC__
    return ((png_charp) PNG_STRING_NEWLINE \
     "libpng version 1.2.52 - November 20, 2014" PNG_STRING_NEWLINE \
     "Copyright (c) 1998-2014 Glenn Randers-Pehrson" PNG_STRING_NEWLINE \
      "Copyright (c) 1996-1997 Andreas Dilger" PNG_STRING_NEWLINE \
      "Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc." \
      PNG_STRING_NEWLINE);
 #else
      return ((png_charp) "libpng version 1.2.52 - November 20, 2014\
      Copyright (c) 1998-2014 Glenn Randers-Pehrson\
       Copyright (c) 1996-1997 Andreas Dilger\
       Copyright (c) 1995-1996 Guy Eric Schalnat, Group 42, Inc.");
 #endif
#endif
}

Vulnerability Type: DoS Overflow 
CWE ID: CWE-119
Summary: Multiple buffer overflows in the (1) png_set_PLTE and (2) png_get_PLTE functions in libpng before 1.0.64, 1.1.x and 1.2.x before 1.2.54, 1.3.x and 1.4.x before 1.4.17, 1.5.x before 1.5.24, and 1.6.x before 1.6.19 allow remote attackers to cause a denial of service (application crash) or possibly have unspecified other impact via a small bit-depth value in an IHDR (aka image header) chunk in a PNG image.
Commit Message: third_party/libpng: update to 1.2.54

TBR=darin@chromium.org
BUG=560291

Review URL: https://codereview.chromium.org/1467263003

Cr-Commit-Position: refs/heads/master@{#362298}