[Telemetry] Print trace counters with trace events.

BUG=
R=ernstm@chromium.org

Review URL: https://codereview.chromium.org/58423002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@233076 0039d316-1c4b-4281-b951-d872f2087c98

tools/perf/metrics/timeline.py

@@ -73,3 +73,9 @@ class TimelineMetric(Metric):
       results.Add(event_name, 'ms', total)
       results.Add(event_name + '_max', 'ms', biggest_jank)
       results.Add(event_name + '_avg', 'ms', total / len(times))
+
+    counters_by_name = self._thread_for_tab.parent.counters
+    for counter_name, counter in counters_by_name.iteritems():
+      total = sum(counter.totals)
+      results.Add(counter_name, 'count', total)
+      results.Add(counter_name + '_avg', 'count', total / len(counter.totals))