1 # Copyright 2013 The Chromium Authors. All rights reserved. 2 # Use of this source code is governed by a BSD-style license that can be 3 # found in the LICENSE file. 4 5 class Metric(object): 6 """Base class for all the metrics that are used by telemetry measurements. 7 8 The Metric class represents a way of measuring something. Metrics are 9 helper classes used by PageTests. Each PageTest may use 10 multiple metrics; each metric should be focussed on collecting data 11 about one thing. 12 """ 13 14 @classmethod 15 def CustomizeBrowserOptions(cls, options): 16 """Add browser options that are required by this metric. 17 18 Some metrics do not have any special browser options that need 19 to be added, and they do not need to override this method; by 20 default, no browser options are added. 21 22 To add options here, call options.AppendExtraBrowserArgs(arg). 23 """ 24 pass 25 26 def Start(self, page, tab): 27 """Start collecting data for this metric.""" 28 pass 29 30 def Stop(self, page, tab): 31 """Stop collecting data for this metric (if applicable).""" 32 pass 33 34 def AddResults(self, tab, results): 35 """Add the data collected into the results object for a measurement. 36 37 Metrics may implement AddResults to provide a common way to add results 38 to the PageTestResults in PageTest.ValidateOrMeasurePage -- 39 results should be added with results.AddValue(...). 40 """ 41 raise NotImplementedError() 42
