[GN] Add script to compile assets catalog without using tools/gyp.

build/toolchain/mac/compile_xcassets.py

Index: build/toolchain/mac/compile_xcassets.py
diff --git a/build/toolchain/mac/compile_xcassets.py b/build/toolchain/mac/compile_xcassets.py
new file mode 100644
index 0000000000000000000000000000000000000000..b78854416bab5852420995b49ff181cef29f3544
--- /dev/null
+++ b/build/toolchain/mac/compile_xcassets.py
@@ -0,0 +1,54 @@
+# 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(
+      '--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,))
+
+  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())