diff -up chromium-60.0.3112.78/third_party/libpng/pnglibconf.h.noprefix chromium-60.0.3112.78/third_party/libpng/pnglibconf.h
--- chromium-60.0.3112.78/third_party/libpng/pnglibconf.h.noprefix	2017-08-01 14:42:54.321986758 -0400
+++ third_party/libpng/pnglibconf.h	2017-08-01 14:43:01.493845832 -0400
@@ -225,13 +225,4 @@
 #define PNG_USER_CHUNK_MALLOC_MAX 4000000L
 /* end of chromium settings */
 
-/* chromium prefixing */
-/*
- * This is necessary to build multiple copies of libpng.  We need this while pdfium builds
- * its own copy of libpng.
- */
-#define PNG_PREFIX
-#include "pngprefix.h"
-/* end of chromium prefixing */
-
 #endif /* PNGLCONF_H */