[catapult] Roll forward Chrome reference builds

dependency_manager/dependency_manager/dependency_manager_util.py

Index: dependency_manager/dependency_manager/dependency_manager_util.py
diff --git a/dependency_manager/dependency_manager/dependency_manager_util.py b/dependency_manager/dependency_manager/dependency_manager_util.py
index 7ec2ec632a9f4a49f2d4f4fae3eda64d43f5d03e..ca0174e01dd5b940c23f4bc2023fb792c2af9ff2 100644
--- a/dependency_manager/dependency_manager/dependency_manager_util.py
+++ b/dependency_manager/dependency_manager/dependency_manager_util.py
@@ -5,6 +5,7 @@
 import os
 import shutil
 import stat
+import subprocess
 import sys
 import zipfile_2_7_13 as zipfile
 
@@ -87,6 +88,15 @@ def UnzipArchive(archive_path, unzip_path):
         'Attempting to unzip a non-archive file at %s' % archive_path)
   if not os.path.exists(unzip_path):
     os.makedirs(unzip_path)
+  # The Python ZipFile does not support symbolic links, which makes it
+  # unsuitable for Mac builds. so use ditto instead. crbug.com/700097.
+  if sys.platform.startswith('darwin'):
+    assert os.path.isabs(unzip_path)
+    unzip_cmd = ['ditto', '-x', '-k', archive_path, unzip_path]
+    proc = subprocess.Popen(unzip_cmd, bufsize=0, stdout=subprocess.PIPE,
+                            stderr=subprocess.PIPE)
+    proc.communicate()
+    return
   try:
     with zipfile.ZipFile(archive_path, 'r') as archive:
       VerifySafeArchive(archive)