[telemetry] Implement first version of timeline based measurement

tools/perf/metrics/timeline_based_metric_request.py

+# Copyright 2014 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 re
+
+
+def IsTimelineMetricRequest(event_name):
+  return event_name.startswith('MetricRequest.')
+
+
+def ParseTimelineMetricRequest(event_name):
+  m = re.match('MetricRequest\.(.+)\/(.+)', event_name)
+  assert m
+  return (m.group(1), m.group(2))

[tonyg, 2014/02/26 17:20:04]

style nit: 2 lines between top level definitions

+
+class TimelineBasedMetricRequest(object):
+  def __init__(self, event):
+    x, y = ParseTimelineMetricRequest(event.name)
+    self.logical_name = x
+    self.metric_type = y
+    self.start = event.start
+    self.end = event.end
+
+  def GetResultNameFor(self, result_name):
+    return "%s/%s" % (self.logical_name, result_name)