Android: allow a --single-step for test_runner.py perf.

build/android/pylib/perf/setup.py

 # 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.
 
 """Generates test runner factory and tests for performance tests."""
 
 import json
 import fnmatch
 import logging
 import os
@@ skipping 48 matching lines @@
   Returns:
     A tuple of (TestRunnerFactory, tests).
   """
   if os.path.exists(constants.PERF_OUTPUT_DIR):
     shutil.rmtree(constants.PERF_OUTPUT_DIR)
   os.makedirs(constants.PERF_OUTPUT_DIR)
 
   # Before running the tests, kill any leftover server.
   _KillPendingServers()
 
-  with file(test_options.steps, 'r') as f:
-    tests = json.load(f)
+  if test_options.single_step:
+    # Running a single command, build the tests structure.
+    tests = [['single_step', test_options.single_step]]
+
+  if test_options.steps:
+    with file(test_options.steps, 'r') as f:
+      tests = json.load(f)
 
   # The list is necessary to keep the steps order, but internally
   # the format is squashed from a list of lists into a single dict:
   # [["A", "cmd"], ["B", "cmd"]] into {"A": "cmd", "B": "cmd"}
   sorted_test_names = [i[0] for i in tests]
   tests_dict = dict(tests)
 
   if test_options.test_filter:
     sorted_test_names = fnmatch.filter(sorted_test_names,
                                        test_options.test_filter)
     tests_dict = dict((k, v) for k, v in tests_dict.iteritems()
                       if k in sorted_test_names)
 
   flaky_steps = []
   if test_options.flaky_steps:
     with file(test_options.flaky_steps, 'r') as f:
       flaky_steps = json.load(f)
 
   def TestRunnerFactory(device, shard_index):
     return test_runner.TestRunner(
         test_options, device, tests_dict, flaky_steps)
 
   return (TestRunnerFactory, sorted_test_names)