[telemetry] Make single-benchmark measurements protected and undiscoverable.

tools/perf/benchmarks/spaceport.py

 # Copyright (c) 2012 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.
 
 """Runs spaceport.io's PerfMarks benchmark."""
 
 import logging
 import os
 
 from telemetry import test
 from telemetry.core import util
 from telemetry.page import page_measurement
 from telemetry.page import page_set
 
 
-class SpaceportMeasurement(page_measurement.PageMeasurement):
+class _SpaceportMeasurement(page_measurement.PageMeasurement):
   def CustomizeBrowserOptions(self, options):
     options.AppendExtraBrowserArgs('--disable-gpu-vsync')
 
   def MeasurePage(self, _, tab, results):
     tab.WaitForJavaScriptExpression(
         '!document.getElementById("start-performance-tests").disabled', 60)
 
     tab.ExecuteJavaScript("""
         window.__results = {};
         window.console.log = function(str) {
@@ skipping 20 matching lines @@
     for key in result_dict:
       chart, trace = key.split('.', 1)
       results.Add(trace, 'objects (bigger is better)', float(result_dict[key]),
                   chart_name=chart, data_type='unimportant')
     results.Add('Score', 'objects (bigger is better)',
                 [float(x) for x in result_dict.values()])
 
 
 class Spaceport(test.Test):
   """spaceport.io's PerfMarks benchmark."""
-  test = SpaceportMeasurement
+  test = _SpaceportMeasurement
 
   def CreatePageSet(self, options):
     spaceport_dir = os.path.join(util.GetChromiumSrcDir(), 'chrome', 'test',
         'data', 'third_party', 'spaceport')
     return page_set.PageSet.FromDict(
         {'pages': [{'url': 'file://index.html'}]},
         spaceport_dir)