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

tools/perf/benchmarks/kraken.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 Mozilla's Kraken JavaScript benchmark."""
 
 import os
 
 from telemetry import test
 from telemetry.page import page_measurement
 from telemetry.page import page_set
 
 
 def _Mean(l):
   return float(sum(l)) / len(l) if len(l) > 0 else 0.0
 
 
-class KrakenMeasurement(page_measurement.PageMeasurement):
+class _KrakenMeasurement(page_measurement.PageMeasurement):
   def MeasurePage(self, _, tab, results):
     tab.WaitForDocumentReadyStateToBeComplete()
     tab.WaitForJavaScriptExpression(
         'document.title.indexOf("Results") != -1', 500)
 
     js_get_results = """
 var formElement = document.getElementsByTagName("input")[0];
 decodeURIComponent(formElement.value.split("?")[1]);
 """
     result_dict = eval(tab.EvaluateJavaScript(js_get_results))
     total = 0
     for key in result_dict:
       if key == 'v':
         continue
       results.Add(key, 'ms', result_dict[key], data_type='unimportant')
       total += _Mean(result_dict[key])
     results.Add('Total', 'ms', total)
 
 
 class Kraken(test.Test):
   """Mozilla's Kraken JavaScript benchmark."""
-  test = KrakenMeasurement
+  test = _KrakenMeasurement
 
   def CreatePageSet(self, options):
     return page_set.PageSet.FromDict({
         'archive_data_file': '../data/kraken.json',
         'pages': [
           { 'url': 'http://krakenbenchmark.mozilla.org/kraken-1.1/driver.html' }
           ]
         }, os.path.abspath(__file__))