Add responsiveness_metric for timeline_based_measurement

tools/telemetry/telemetry/web_perf/metrics/unittest_util.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.
+
+class _Result(object):
+  def __init__(self, trace_name, units, value, chart_name, data_type):
+    self.trace_name = trace_name
+    self.units = units
+    self.value = value
+    self.chart_name = chart_name
+    self.data_type = data_type
+
+
+class FakeResults(object):
+  def __init__(self):
+    self._results = {}
+    self._summary_results = {}
+
+  def Add(self, trace_name, units, value, chart_name=None, data_type='default'):
+    self._results[trace_name] = _Result(trace_name, units, value, chart_name,
+                                        data_type)
+
+  def AddSummary(self, trace_name, units, value, chart_name=None,
+                 data_type='default'):
+    self._summary_results[trace_name] = _Result(trace_name, units, value,
+                                                chart_name, data_type)
+
+  def GetResult(self, trace_name):
+    return self._results.get(trace_name)
+
+  def GetSummaryResult(self, trace_name):
+    return self._summary_results.get(trace_name)