Revert of Do not allow asan_symbolize.py to fall back to addr2line/atos.

tools/valgrind/asan/asan_symbolize.py

 #!/usr/bin/env python
 
 # Copyright (c) 2012 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.
 
 from third_party import asan_symbolize
 
 import argparse
 import base64
@@ skipping 228 matching lines @@
   parser.add_argument('strip_path_prefix', nargs='*',
       help='When printing source file names, the longest prefix ending in one '
            'of these substrings will be stripped. E.g.: "Release/../../".')
   parser.add_argument('--executable-path',
       help='Path to program executable. Used on OSX swarming bots to locate '
            'dSYM bundles for associated frameworks and bundles.')
   args = parser.parse_args()
 
   disable_buffering()
   set_symbolizer_path()
-  # Disallow fallback to addr2line/atos if llvm-symbolizer is not present. Those
-  # are slow and we don't want to use them ever.
-  asan_symbolize.allow_system_symbolizer = False
   asan_symbolize.demangle = True
   asan_symbolize.fix_filename_patterns = args.strip_path_prefix
   # Most source paths for Chromium binaries start with
   # /path/to/src/out/Release/../../
   asan_symbolize.fix_filename_patterns.append('Release/../../')
   binary_name_filter = None
   if platform.uname()[0] == 'Darwin':
     binary_name_filter = make_chrome_osx_binary_name_filter(
         chrome_product_dir_path(args.executable_path))
   loop = asan_symbolize.SymbolizationLoop(
       binary_name_filter=binary_name_filter,
       dsym_hint_producer=chrome_dsym_hints)
 
   if args.test_summary_json_file:
     symbolize_snippets_in_json(args.test_summary_json_file, loop)
   else:
     # Process stdin.
     asan_symbolize.logfile = sys.stdin
     loop.process_logfile()
 
 if __name__ == '__main__':
   main()