[Telemetry] Add an example for adding an end to end Telemetry benchmark

tools/telemetry/examples/benchmarks/message_loop_benchmark.py

+# Copyright 2015 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.
+from telemetry import benchmark
+from telemetry.timeline import tracing_category_filter
+from telemetry.web_perf import timeline_based_measurement
+
+from benchmarks import simple_story_set
+from benchmarks import message_loop_metric
+
+
+class MessageLoopBenchmark(benchmark.Benchmark):
+
+  def CreateStorySet(self, options):
+    return simple_story_set.SimpleStorySet()
+
+  def CreateTimelineBasedMeasurementOptions(self):
+    cat_filter = tracing_category_filter.CreateMinimalOverheadFilter()
+    cat_filter.AddIncludedCategory('*')

[eakuefner, 2015/10/30 00:14:55]

Can we maybe expand this to first add blink.console explicitly to show that it's
required?

[nednguyen, 2015/10/30 16:29:56]

Good call

+    options = timeline_based_measurement.Options(overhead_level=cat_filter)
+    options.SetTimelineBasedMetrics(
+        [message_loop_metric.MessageLoopLatencyMetric()])
+    return options
+
+  @classmethod
+  def Name(cls):
+    return 'message_loop_counter.simple_story'