[iOS/Mac/GN] Update timestamp when copying a tree.

build/toolchain/mac/compile_xcassets.py

 # Copyright 2016 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.
 
 import argparse
 import os
 import sys
 
 
 def Main():
   parser = argparse.ArgumentParser(
       description='compile assets catalog for a bundle')
   parser.add_argument(
+      '--version-for-gn', choices=('1',),
+      help='version need to be increased in this script and in the file '
+           '//build/toolchain/mac/BUILD.gn to force build until issue '
+           'http://crbug.com/619083 is fixed')
+  parser.add_argument(
       '--platform', '-p', required=True,
       choices=('macosx', 'iphoneos', 'iphonesimulator'),
       help='target platform for the compiled assets catalog')
   parser.add_argument(
       '--minimum-deployment-target', '-t', required=True,
       help='minimum deployment target for the compiled assets catalog')
   parser.add_argument(
       '--output', '-o', required=True,
       help='path to the compiled assets catalog')
   parser.add_argument(
       'inputs', nargs='+',
       help='path to input assets catalog sources')
   args = parser.parse_args()
 
   if os.path.basename(args.output) != 'Assets.car':
     sys.stderr.write(
         'output should be path to compiled asset catalog, not '
         'to the containing bundle: %s\n' % (args.output,))
 
+  if os.path.exists(args.output):
+    os.unlink(args.output)
+
   command = [
       'xcrun', 'actool', '--output-format', 'human-readable-text',
       '--compress-pngs', '--notices', '--warnings', '--errors',
       '--platform', args.platform, '--minimum-deployment-target',
       args.minimum_deployment_target,
   ]
 
   if args.platform == 'macosx':
     command.extend(['--target-device', 'mac'])
   else:
     command.extend(['--target-device', 'iphone', '--target-device', 'ipad'])
 
   # actool crashes if paths are relative, so use os.path.abspath to get absolute
   # path for input and outputs.
   command.extend(['--compile', os.path.abspath(os.path.dirname(args.output))])
   command.extend(map(os.path.abspath, args.inputs))
 
   os.execvp('xcrun', command)
   sys.exit(1)
 
 if __name__ == '__main__':
   sys.exit(Main())