Allow benchmarks to specify running multiple metrics.

tracing/tracing/metrics/metric_runner.py

Index: tracing/tracing/metrics/metric_runner.py
diff --git a/tracing/tracing/metrics/metric_runner.py b/tracing/tracing/metrics/metric_runner.py
index 62ac454ed42b917501c02a55db0b6f985d74f58c..873f4b37dabe9b0748716b3be917e6cd1edb5222 100644
--- a/tracing/tracing/metrics/metric_runner.py
+++ b/tracing/tracing/metrics/metric_runner.py
@@ -16,27 +16,29 @@ _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,