Allow benchmarks to specify running multiple metrics.

tracing/bin/run_metric

Index: tracing/bin/run_metric
diff --git a/tracing/bin/run_metric b/tracing/bin/run_metric
index 91a0eb35fb8cc0bdf1c94b0b24e8072a611e3504..6e29c18d190099217a1f301e480ece1cdf32481a 100755
--- a/tracing/bin/run_metric
+++ b/tracing/bin/run_metric
@@ -17,25 +17,26 @@ def Main(argv):
       ['/tracing/metrics/all_metrics.html'])
   parser = argparse.ArgumentParser(
       description='Runs metrics on local traces')
-  parser.add_argument('metric_name',
-                      help=('The function name of a registered metric, NOT '
-                      'filename. Available metrics are: %s' %
-                      ', '.join(all_metrics)),
-                      choices=all_metrics, metavar='metricName')
   parser.add_argument('trace_file_or_dir',
                       help='A trace file, or a dir containing trace files')
+  parser.add_argument('metrics', nargs=argparse.REMAINDER,
+                      help=('Function names of registered metrics '
+                            '(not filenames.) '
+                            'Available metrics are: %s' %
+                            ', '.join(all_metrics)),
+                      choices=all_metrics, metavar='metricName')
 
   args = parser.parse_args(argv[1:])
-  metric = args.metric_name
+  trace_file_or_dir = os.path.abspath(args.trace_file_or_dir)
 
-  if os.path.isdir(args.trace_file_or_dir):
-    trace_dir = args.trace_file_or_dir
+  if os.path.isdir(trace_file_or_dir):
+    trace_dir = trace_file_or_dir
     traces = [os.path.join(trace_dir, trace) for trace in os.listdir(trace_dir)]
   else:
-    traces = [args.trace_file_or_dir]
+    traces = [trace_file_or_dir]
 
-  results = {k: v.AsDict()
-      for k, v in metric_runner.RunMetricOnTraces(traces, metric).iteritems()}
+  results = {k: v.AsDict() for k, v in 
+             metric_runner.RunMetricOnTraces(traces, args.metrics).iteritems()}
 
   failures = []
   for trace in traces: