telemetry: separated stats collection from metrics calculation.

tools/perf/run_tests

 #!/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.
 """This script runs unit tests of the code in the perf directory.
 
 This script DOES NOT run benchmarks. run_benchmarks and run_measurement do that.
 """
 
 import os
 import sys
 
 import measurements
 import perf_tools
 from telemetry.unittest import gtest_testrunner
 from telemetry.unittest import run_tests
 
 if __name__ == '__main__':
   top_level_dir = os.path.abspath(os.path.dirname(__file__))
   runner = gtest_testrunner.GTestTestRunner(print_result_after_run=False)
 
   start_dir = 'measurements'
   ret = run_tests.Main(sys.argv[1:], start_dir, top_level_dir, runner)
 
   start_dir = 'perf_tools'
   ret += run_tests.Main(sys.argv[1:], start_dir, top_level_dir, runner)
 
+  start_dir = 'metrics'
+  ret += run_tests.Main(sys.argv[1:], start_dir, top_level_dir, runner)
+
   if runner.result:
     runner.result.PrintSummary()
     sys.exit(min(ret + runner.result.num_errors, 255))
   else:
     sys.exit(ret)