Remove all ancillary chunks except for tRNS

build/sanitize-png-files.sh

 #!/bin/bash
 # Copyright (c) 2010 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 ALL_DIRS="
 ash/resources
 ui/resources
 chrome/app/theme
 chrome/browser/resources
 chrome/renderer/resources
 webkit/glue/resources
 remoting/resources
 remoting/webapp
 "
 
 function sanitize_file {
   tput el
   echo -ne "$1\r"
   local file=$1
   local name=$(basename $file)
-  pngcrush -d $TMP_DIR -brute -reduce -rem text -rem mkBT \
-      -rem mkTS $file > /dev/null
+  # -rem alla removes all ancillary chunks except for tRNS
+  pngcrush -d $TMP_DIR -brute -reduce -rem alla $file > /dev/null
+
   mv "$TMP_DIR/$name" "$file"
 }
 
 function sanitize_dir {
   local dir=$1
   for f in $(find $dir -name "*.png"); do
     sanitize_file $f
   done
 }
 
@@ skipping 19 matching lines @@
 # If no arguments passed, sanitize all directories.
 DIRS=$*
 set ${DIRS:=$ALL_DIRS}
 
 for d in $DIRS; do
   echo "Sanitizing png files in $d"
   sanitize_dir $d
   echo
 done