[Android] Add ability to generate test trace json for perf tests runs.

build/android/test_runner.py

 #!/usr/bin/env python
 #
 # Copyright 2013 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.
 
 """Runs all types of tests from one unified interface."""
 
 import argparse
 import collections
@@ skipping 538 matching lines @@
   group.add_argument('--known-devices-file', help='Path to known device list.')
   group.add_argument(
       '--repeat', dest='repeat', type=int, default=0,
       help='Number of times to repeat the specified set of tests.')
   group.add_argument(
       '--break-on-failure', '--break_on_failure', dest='break_on_failure',
       action='store_true', help='Whether to break on failure.')
   group.add_argument(
       '--write-buildbot-json', action='store_true',
       help='Whether to output buildbot json.')
+  # TODO(rnephew): Move up to top level options when implemented on all tests.
+  group.add_argument(
+      '--trace-output', metavar='FILENAME', type=os.path.realpath,
+      help='Path to save test_runner trace data to.')
   AddCommonOptions(parser)
   AddDeviceOptions(parser)
 
 
 def AddPythonTestOptions(parser):
   group = parser.add_argument_group('Python Test Options')
   group.add_argument(
       '-s', '--suite', dest='suite_name', metavar='SUITE_NAME',
       choices=constants.PYTHON_UNIT_TEST_SUITES.keys(),
       help='Name of the test suite to run.')
@@ skipping 311 matching lines @@
     if e.is_infra_error:
       return constants.INFRA_EXIT_CODE
     return constants.ERROR_EXIT_CODE
   except: # pylint: disable=W0702
     logging.exception('Unrecognized error occurred.')
     return constants.ERROR_EXIT_CODE
 
 
 if __name__ == '__main__':
   sys.exit(main())