disable field trials if the build is 30 days or older

base/metrics/field_trial.h

Index: base/metrics/field_trial.h
===================================================================
--- base/metrics/field_trial.h	(revision 70854)
+++ base/metrics/field_trial.h	(working copy)
@@ -94,6 +94,13 @@
   // to the total_probability.
   FieldTrial(const std::string& name, Probability total_probability);
 
+  // Determine if the field trial is to be disabled or not based on
+  // disable_duration_, build time of the module and Now(). This method sets
+  // disable_field_trail_ to true, if the difference between build time of the

[jar (doing other things), 2011/01/10 22:01:21]

nit: trail-->trial

[rtenneti, 2011/01/10 22:48:03]

Done.

+  // module and Now() is greater than disable_duration_. If disable_field_trail_
+  // is true then the field trial reverts to the 'default' bucket.
+  void FieldTrial::DetermineIfFieldTrailIsToBeDisabled();
+
   // Establish the name and probability of the next group in this trial.
   // Sometimes, based on construction randomization, this call may causes the
   // provided group to be *THE* group selected for use in this instance.
@@ -112,6 +119,13 @@
   // number is used as the group name.
   std::string group_name() const { return group_name_; }
 
+  // Set the duration from build time of the module to disable Field Trial.
+  void SetDisableDuration(const base::TimeDelta& duration);
+
+  base::TimeDelta disableDuration() const {

[jar (doing other things), 2011/01/10 22:01:21]

nit: Reading this name, it looks like the duration for which this will be
disabled, rather than the (much loo long name) duration until it will be
impossible to enable.

We need a better name forthe setter and slot.  Possibilities include:

InhibitDate
UsageTimeout
EnablementDeadline

WDYT?

[rtenneti, 2011/01/10 22:48:03]

Hi Jim,
  UsageTimeout seems to read better. Going with it. Hope that is ok.

thanks,
raman

[rtenneti, 2011/01/10 22:48:03]

Done.

+    return disable_duration_;
+  }
+
   // Helper function for the most common use: as an argument to specifiy the
   // name of a HISTOGRAM.  Use the original histogram name as the name_prefix.
   static std::string MakeName(const std::string& name_prefix,
@@ -120,6 +134,9 @@
   // Enable benchmarking sets field trials to a common setting.
   static void EnableBenchmarking();
 
+  // Get build time.
+  static Time GetBuildTime();
+
  private:
   friend class RefCounted<FieldTrial>;
 
@@ -143,6 +160,14 @@
 
   int next_group_number_;
 
+  // The default value (all remaining probabilities) can be selected after the
+  // duration, which is based on the build time of the module.
+  base::TimeDelta disable_duration_;
+
+  // When disable_field_trail_ is true, field trial reverts to the 'default'
+  // bucket.
+  bool disable_field_trail_;
+
   // The pseudo-randomly assigned group number.
   // This is kNotParticipating if no group has been assigned.
   int group_;