Add profiling_controller that manages profilers.

tools/perf/measurements/loading_profile.py

 # Copyright 2013 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.
 
 import os
 import tempfile
 
 from metrics import loading
 from telemetry.core.platform.profiler import perf_profiler
 from telemetry.page import page_test
 from telemetry.value import scalar
 
 
 class LoadingProfile(page_test.PageTest):
   options = {'page_repeat': 2}
 
   def __init__(self):
     super(LoadingProfile, self).__init__(discard_first_result=True)
 
   def CustomizeBrowserOptions(self, options):
     if not perf_profiler.PerfProfiler.is_supported(browser_type='any'):
       raise Exception('This measurement is not supported on this platform')
 
     perf_profiler.PerfProfiler.CustomizeBrowserOptions(
         browser_type='any', options=options)
 
   def WillNavigateToPage(self, page, tab):
-    tab.browser.StartProfiling(perf_profiler.PerfProfiler.name(),
-                               os.path.join(tempfile.mkdtemp(),
-                                            page.file_safe_name))
+    tab.browser.platform.profiling_controller.StartProfiling(
+        perf_profiler.PerfProfiler.name(),
+        os.path.join(tempfile.mkdtemp(), page.file_safe_name))
 
   def ValidateAndMeasurePage(self, page, tab, results):
     # In current telemetry tests, all tests wait for DocumentComplete state,
     # but we need to wait for the load event.
     tab.WaitForJavaScriptExpression('performance.timing.loadEventStart', 300)
 
     profile_files = tab.browser.StopProfiling()

[tonyg, 2014/09/04 17:10:19]

How does this work?

Note that we could simply remove this Measurement if it's in the way. I'm not
aware of anyone using it and I've always thought it is kind of strange for a
Measurement to try to do something with a Profiler.

[nednguyen, 2014/09/04 17:31:46]

Removing patch in https://codereview.chromium.org/540483004/

 
     loading.LoadingMetric().AddResults(tab, results)
 
     profile_file = None
     for profile_file in profile_files:
       if 'renderer' in profile_file:
         break
 
     for function, period in perf_profiler.PerfProfiler.GetTopSamples(
         profile_file, 10).iteritems():
       results.AddValue(scalar.ScalarValue(
           results.current_page, function.replace('.', '_'), 'period', period))