Implement shortcut for finalizing a trial with all remaining probability

It is helpful when defining experiments to put all remaining probability
on the final (often the "control" group), without having to keep a careful
tally of assignments of probabilities.  This CL implements that functionality.

r=rvargas
Review URL: http://codereview.chromium.org/150141

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@19696 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 5 insertions, 3 deletions

diff --git a/base/field_trial.h b/base/field_trial.h
index 6d3c101..fba0b01 100644
--- a/base/field_trial.h
+++ b/base/field_trial.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2006-2009 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.
 
@@ -50,7 +50,7 @@
 //                                       "MemoryExperiment").data(), count);
 
 // The above code will create 3 distinct histograms, with each run of the
-// application being assigned to of of teh three groups, and for each group, the
+// application being assigned to of of the three groups, and for each group, the
 // correspondingly named histogram will be populated:
 
 // Memory.RendererTotal            // 96% of users still fill this histogram.
@@ -80,7 +80,9 @@ class FieldTrial : public base::RefCounted<FieldTrial> {
 
   // Provide an easy way to assign all remaining probability to a group.  Note
   // that this will force an instance to participate, and make it illegal to
-  // attempt to probabalistically add any other groups to the trial.
+  // attempt to probabalistically add any other groups to the trial.  When doing
+  // A/B tests with timings, it is often best to define all groups, so that
+  // histograms will get unique names via the MakeName() methods.
   static const Probability kAllRemainingProbability;
 
   // The name is used to register the instance with the FieldTrialList class,