Fix problem where field trials using kExpirationYearInFuture could get disabled.

base/metrics/field_trial.cc

 // 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.
 
 #include "base/metrics/field_trial.h"
 
 #include "base/build_time.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/rand_util.h"
@@ skipping 31 matching lines @@
 }  // namespace
 
 static const char kHistogramFieldTrialSeparator('_');
 
 // statics
 const int FieldTrial::kNotFinalized = -1;
 const int FieldTrial::kDefaultGroupNumber = 0;
 bool FieldTrial::enable_benchmarking_ = false;
 
 const char FieldTrialList::kPersistentStringSeparator('/');
-int FieldTrialList::kExpirationYearInFuture = 0;
+int FieldTrialList::kExpirationYearNotExpired = 0;
 
 //------------------------------------------------------------------------------
 // FieldTrial methods and members.
 
 FieldTrial::FieldTrial(const std::string& trial_name,
                        const Probability total_probability,
                        const std::string& default_group_name)
     : trial_name_(trial_name),
       divisor_(total_probability),
       default_group_name_(default_group_name),
@@ skipping 174 matching lines @@
 
 FieldTrialList::FieldTrialList(
     const FieldTrial::EntropyProvider* entropy_provider)
     : entropy_provider_(entropy_provider),
       observer_list_(new ObserverListThreadSafe<FieldTrialList::Observer>(
           ObserverListBase<FieldTrialList::Observer>::NOTIFY_EXISTING_ONLY)) {
   DCHECK(!global_);
   DCHECK(!used_without_global_);
   global_ = this;
 
+  Time two_years_from_build_time = GetBuildTime() + TimeDelta::FromDays(730);
   Time::Exploded exploded;
-  Time two_years_from_now =
-      Time::NowFromSystemTime() + TimeDelta::FromDays(730);
-  two_years_from_now.LocalExplode(&exploded);
-  kExpirationYearInFuture = exploded.year;
+  two_years_from_build_time.LocalExplode(&exploded);
+  kExpirationYearNotExpired = exploded.year;
 }
 
 FieldTrialList::~FieldTrialList() {
   AutoLock auto_lock(lock_);
   while (!registered_.empty()) {
     RegistrationList::iterator it = registered_.begin();
     it->second->Release();
     registered_.erase(it->first);
   }
   DCHECK_EQ(this, global_);
@@ skipping 224 matching lines @@
     used_without_global_ = true;
     return;
   }
   AutoLock auto_lock(global_->lock_);
   DCHECK(!global_->PreLockedFind(trial->trial_name()));
   trial->AddRef();
   global_->registered_[trial->trial_name()] = trial;
 }
 
 }  // namespace base