Test CL to demonstrate GN + hermetic toolchain

build/config/mac/compile_xib.py

Index: build/config/mac/compile_xib.py
diff --git a/build/config/mac/compile_xib.py b/build/config/mac/compile_xib.py
index 845f8c179550bbd339cbd306a008671cf8573607..f1e04ddbdd751f52e14bed5eac3ce2062273a543 100644
--- a/build/config/mac/compile_xib.py
+++ b/build/config/mac/compile_xib.py
@@ -4,6 +4,7 @@
 
 
 import argparse
+import logging
 import os
 import re
 import subprocess
@@ -18,13 +19,19 @@ def main():
                       help='Path to output bundle.')
   parser.add_argument('-i', '--input', required=True,
                       help='Path to input xib or storyboard.')
+  parser.add_argument('--developer_dir', required=False,
+                      help='Path to ibtool.')
   args, unknown_args = parser.parse_known_args()
 
-  ibtool_args = [
-      'xcrun', 'ibtool',
+  ibtool_args = ['xcrun', 'ibtool']
+  if (args.developer_dir):
+    os.environ['DEVELOPER_DIR'] = args.developer_dir
+    # ibtools_args = [ args.ibtool_path ]
+
+  ibtool_args.extend([
       '--errors', '--warnings', '--notices',
       '--output-format', 'human-readable-text'
-  ]
+  ])
   ibtool_args += unknown_args
   ibtool_args += [
       '--compile',