Save the logcat file in isolated directory.

build/android/test_wrapper/logdog_wrapper.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.
 
 """Wrapper for adding logdog streaming support to swarming tasks."""
 
 import argparse
 import logging
 import os
@@ skipping 18 matching lines @@
 
 def CommandParser():
   # Parses the command line arguments being passed in
   parser = argparse.ArgumentParser()
   parser.add_argument('--target', required=True,
                       help='The test target to be run.')
   parser.add_argument('--logdog-bin-cmd', required=True,
                       help='The logdog bin cmd.')
   parser.add_argument('--target-devices-file', required=False,
                       help='The target devices file.')
+  parser.add_argument('--logcat-output-file',
+                      help='The logcat output file.')
   return parser
 
 def CreateStopTestsMethod(proc):
   def StopTests(signum, _frame):
     logging.error('Forwarding signal %s to test process', str(signum))
     proc.send_signal(signum)
   return StopTests
 
 def main():
   parser = CommandParser()
   args, extra_cmd_args = parser.parse_known_args(sys.argv[1:])
 
   logging.basicConfig(level=logging.INFO)
   with tempfile_ext.NamedTemporaryDirectory() as logcat_output_dir:
     test_cmd = [
         os.path.join('bin', 'run_%s' % args.target),
-        '--logcat-output-file', os.path.join(logcat_output_dir, 'logcats'),
+        '--logcat-output-file',
+        (args.logcat_output_file if args.logcat_output_file
+            else os.path.join(logcat_output_dir, 'logcats')),
         '--upload-logcats-file',
         '--target-devices-file', args.target_devices_file,
         '-v'] + extra_cmd_args
 
     with tempfile_ext.NamedTemporaryDirectory(
         prefix='tmp_android_logdog_wrapper') as temp_directory:
       if not os.path.exists(args.logdog_bin_cmd):
         logging.error(
             'Logdog binary %s unavailable. Unable to create logdog client',
             args.logdog_bin_cmd)
@@ skipping 13 matching lines @@
             'run', '-streamserver-uri', streamserver_uri, '--'] + test_cmd
 
       test_proc = subprocess.Popen(test_cmd)
       with signal_handler.SignalHandler(signal.SIGTERM,
                                         CreateStopTestsMethod(test_proc)):
         result = test_proc.wait()
     return result
 
 if __name__ == '__main__':
   sys.exit(main())