Add BUILD.gn rules to compile third_party/class-dump.

third_party/class-dump/class-dump.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.
+
+# Wrapper around class-dump to allow gn build to run the tool (as action
+# target can only run python scripts). Also filters the output to remove
+# all cxx_destruct lines that are not understood from class-dump output.
+
+import argparse
+import errno
+import os
+import subprocess
+import sys
+
+
+def Main(args):
+  parser = argparse.ArgumentParser('wrapper around class-dump')
+  parser.add_argument(
+      '-o', '--output', required=True,
+      help='name of the output file')
+  parser.add_argument(
+      '-t', '--class-dump-path', required=True,
+      help='path to class-dump executable')
+  parser.add_argument(
+      'args', nargs='*',
+      help='arguments to pass to class-dump')
+  args = parser.parse_args(args)
+
+  try:
+    os.makedirs(os.path.dirname(args.output))
+  except OSError, e:
+    if e.errno != errno.EEXIST:
+      raise
+
+  process = subprocess.Popen(
+      [args.class_dump_path] + args.args,
+      stdout=subprocess.PIPE,
+      stderr=subprocess.PIPE)
+  stdout, stderr = process.communicate()
+  if process.returncode != 0:
+    sys.stderr.write(stderr)
+    sys.exit(process.returncode)
+
+  with open(args.output, 'wb') as output:
+    output.write("// Treat class-dump output as a system header.\n")
+    output.write("#pragma clang system_header\n")
+    for line in stdout.splitlines():
+      if 'cxx_destruct' in line:
+        continue
+      output.write(line)
+      output.write('\n')
+
+
+if __name__ == '__main__':
+  Main(sys.argv[1:])