Allow benchmarks to specify running multiple metrics.

tracing/tracing/metrics/metric_runner.py

 # 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.
 import os
 
 from perf_insights.mre import function_handle
 from perf_insights.mre import map_runner
 from perf_insights.mre import progress_reporter
 from perf_insights.mre import file_handle
 from perf_insights.mre import job as job_module
 
 _METRIC_MAP_FUNCTION_FILENAME = 'metric_map_function.html'
 
 _METRIC_MAP_FUNCTION_NAME = 'metricMapFunction'
 
 def _GetMetricsDir():
   return os.path.dirname(os.path.abspath(__file__))
 
-def _GetMetricRunnerHandle(metric):
-  assert isinstance(metric, basestring)
+def _GetMetricRunnerHandle(metrics):
+  assert isinstance(metrics, list)
+  for metric in metrics:
+    assert isinstance(metric, basestring)
   metrics_dir = _GetMetricsDir()
   metric_mapper_path = os.path.join(metrics_dir, _METRIC_MAP_FUNCTION_FILENAME)
 
   modules_to_load = [function_handle.ModuleToLoad(filename=metric_mapper_path)]
-  options = {'metric': metric}
+  options = {'metrics': metrics}
   map_function_handle = function_handle.FunctionHandle(
       modules_to_load, _METRIC_MAP_FUNCTION_NAME, options)
 
   return job_module.Job(map_function_handle, None)
 
-def RunMetric(filename, metric, extra_import_options=None):
-  result = RunMetricOnTraces([filename], metric, extra_import_options)
+def RunMetric(filename, metrics, extra_import_options=None):
+  result = RunMetricOnTraces([filename], metrics, extra_import_options)
   return result[filename]
 
-def RunMetricOnTraces(filenames, metric,
+def RunMetricOnTraces(filenames, metrics,
                       extra_import_options=None):
   trace_handles = [
       file_handle.URLFileHandle(f, 'file://%s' % f) for f in filenames]
-  job = _GetMetricRunnerHandle(metric)
+  job = _GetMetricRunnerHandle(metrics)
   runner = map_runner.MapRunner(
-      trace_handles, job,
-      extra_import_options=extra_import_options,
+      trace_handles, job, extra_import_options=extra_import_options,
       progress_reporter=progress_reporter.ProgressReporter())
   map_results = runner.RunMapper()
   return map_results