Check libpng directly into third_party/

third_party/libpng/contrib/visupng/PngFile.h

Index: third_party/libpng/contrib/visupng/PngFile.h
diff --git a/third_party/libpng/contrib/visupng/PngFile.h b/third_party/libpng/contrib/visupng/PngFile.h
new file mode 100644
index 0000000000000000000000000000000000000000..474426c22ea5625cd13c65fed39254bff9c372fc
--- /dev/null
+++ b/third_party/libpng/contrib/visupng/PngFile.h
@@ -0,0 +1,30 @@
+/*------------------------------------------*/
+/*  PNGFILE.H -- Header File for pngfile.c*/
+/*------------------------------------------*/
+
+/* Copyright 2000, Willem van Schaik.*/
+
+/* This code is released under the libpng license.*/
+/* For conditions of distribution and use, see the disclaimer*/
+/* and license in png.h*/
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <windows.h>
+
+void PngFileInitialize (HWND hwnd) ;
+BOOL PngFileOpenDlg (HWND hwnd, PTSTR pstrFileName, PTSTR pstrTitleName) ;
+BOOL PngFileSaveDlg (HWND hwnd, PTSTR pstrFileName, PTSTR pstrTitleName) ;
+
+BOOL PngLoadImage (PTSTR pstrFileName, png_byte **ppbImageData,
+                   int *piWidth, int *piHeight, int *piChannels, png_color *pBkgColor);
+BOOL PngSaveImage (PTSTR pstrFileName, png_byte *pDiData,
+                   int iWidth, int iHeight, png_color BkgColor);
+
+#ifndef PNG_STDIO_SUPPORTED
+static void png_read_data(png_structp png_ptr, png_bytep data, png_size_t length);
+static void png_write_data(png_structp png_ptr, png_bytep data, png_size_t length);
+static void png_flush(png_structp png_ptr);
+#endif
+