Add resource whitelisting compatibility for offical builder scripts.

tools/resources/generate_resource_whitelist.py

 #!/usr/bin/env python
 # 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 re
 import sys
 
@@ skipping 37 matching lines @@
       r'^#define (%s) _Pragma\S+ (\d+)$' % '|'.join(resource_names))
   with open(header, 'r') as f:
     res_ids = [ int(pattern.match(line).group(2))
                  for line in f if pattern.match(line) ]
   if len(res_ids) != len(resource_names):
     raise Exception('Find resource id failed: the result is ' +
                     ', '.join(str(i) for i in res_ids))
   return set(res_ids)
 
 
+# TODO(estevenson): Remove this after updating official build scripts.
+def _GetResourceIdsInPragmaWarnings(input):
+   """Returns set of resource ids that are inside unknown pragma warnings
+      for the given input.
+   """
+   used_resources = set()
+   unknown_pragma_warning_pattern = re.compile(
+       'whitelisted_resource_(?P<resource_id>[0-9]+)')
+   for ln in input:
+     match = unknown_pragma_warning_pattern.search(ln)
+     if match:
+       resource_id = int(match.group('resource_id'))
+       used_resources.add(resource_id)
+   return used_resources
+
+
 def main():
   parser = argparse.ArgumentParser(usage=USAGE)
   parser.add_argument(
       '-i', '--input', type=argparse.FileType('r'), default=sys.stdin,
       help='A resource whitelist where each line contains one resource ID')
   parser.add_argument(
       '-o', '--output', type=argparse.FileType('w'), default=sys.stdout,
       help='The resource list path to write (default stdout)')
   parser.add_argument(
       '--out-dir', required=True,
       help='The out target directory, for example out/Release')
+  parser.add_argument(
+      '--use-existing-resource-ids', action='store_true', default=False,
+      help='Specifies that the input file already contains resource ids')
 
   args = parser.parse_args()
 
   used_resources = set()
-  used_resources.update([int(resource_id) for resource_id in args.input])
+  if args.use_existing_resource_ids:
+    used_resources.update([int(resource_id) for resource_id in args.input])
+  else:
+    used_resources.update(_GetResourceIdsInPragmaWarnings(args.input))
+
   used_resources |= _FindResourceIds(
       os.path.join(args.out_dir, COMPONENTS_STRINGS_HEADER),
       ARCH_SPECIFIC_RESOURCES)
 
   for resource_id in sorted(used_resources):
     args.output.write('%d\n' % resource_id)
 
 if __name__ == '__main__':
   main()