Update documentation comments in field_trial.h.

base/metrics/field_trial.h

 // 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.
 
 // FieldTrial is a class for handling details of statistical experiments
 // performed by actual users in the field (i.e., in a shipped or beta product).
 // All code is called exclusively on the UI thread currently.
 //
 // The simplest example is an experiment to see whether one of two options
 // produces "better" results across our user population.  In that scenario, UMA
@@ skipping 20 matching lines @@
 // Somewhere in main thread initialization code, we'd probably define an
 // instance of a FieldTrial, with code such as:
 
 // // FieldTrials are reference counted, and persist automagically until
 // // process teardown, courtesy of their automatic registration in
 // // FieldTrialList.
 // // Note: This field trial will run in Chrome instances compiled through
 // //       8 July, 2015, and after that all instances will be in "StandardMem".
 // scoped_refptr<base::FieldTrial> trial(
 //     base::FieldTrialList::FactoryGetFieldTrial("MemoryExperiment", 1000,
-//                                                "StandardMem", 2015, 7, 8));
-// const int kHighMemGroup =
+//                                                "StandardMem", 2015, 7, 8,
+//                                                NULL));
+// const int high_mem_group =
 //     trial->AppendGroup("HighMem", 20);  // 2% in HighMem group.
-// const int kLowMemGroup =
+// const int low_mem_group =
 //     trial->AppendGroup("LowMem", 20);   // 2% in LowMem group.
 // // Take action depending of which group we randomly land in.
-// if (trial->group() == kHighMemGroup)
+// if (trial->group() == high_mem_group)
 //   SetPruningAlgorithm(kType1);  // Sample setting of browser state.
-// else if (trial->group() == kLowMemGroup)
+// else if (trial->group() == low_mem_group)
 //   SetPruningAlgorithm(kType2);  // Sample alternate setting.
 
 // We then, in addition to our original histogram, output histograms which have
 // slightly different names depending on what group the trial instance happened
 // to randomly be assigned:
 
 // HISTOGRAM_COUNTS("Memory.RendererTotal", count);  // The original histogram.
 // static const bool memory_renderer_total_trial_exists =
 //     FieldTrialList::TrialExists("MemoryExperiment");
 // if (memory_renderer_total_trial_exists) {
@@ skipping 374 matching lines @@
 
   // List of observers to be notified when a group is selected for a FieldTrial.
   scoped_refptr<ObserverListThreadSafe<Observer> > observer_list_;
 
   DISALLOW_COPY_AND_ASSIGN(FieldTrialList);
 };
 
 }  // namespace base
 
 #endif  // BASE_METRICS_FIELD_TRIAL_H_