Plumbing for variations headers from synthetic field trials.

components/metrics/metrics_service.cc

 // Copyright 2014 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.
 
 //------------------------------------------------------------------------------
 // Description of the life cycle of a instance of MetricsService.
 //
 //  OVERVIEW
 //
 // A MetricsService instance is typically created at application startup.  It is
@@ skipping 1120 matching lines @@
   int64 value = local_state_->GetInt64(path);
   local_state_->SetInt64(path, value + 1);
 }
 
 bool MetricsService::UmaMetricsProperlyShutdown() {
   CHECK(clean_shutdown_status_ == CLEANLY_SHUTDOWN ||
         clean_shutdown_status_ == NEED_TO_SHUTDOWN);
   return clean_shutdown_status_ == CLEANLY_SHUTDOWN;
 }
 
+void MetricsService::AddSyntheticTrialObserver(
+    SyntheticTrialObserver* observer) {
+  synthetic_trial_observer_list_.AddObserver(observer);
+  if (!synthetic_trial_groups_.empty())
+    observer->OnSyntheticTrialsChanged(synthetic_trial_groups_);
+}
+
+void MetricsService::RemoveSyntheticTrialObserver(
+    SyntheticTrialObserver* observer) {
+  synthetic_trial_observer_list_.RemoveObserver(observer);
+}
+
 void MetricsService::RegisterSyntheticFieldTrial(
     const SyntheticTrialGroup& trial) {
   for (size_t i = 0; i < synthetic_trial_groups_.size(); ++i) {
     if (synthetic_trial_groups_[i].id.name == trial.id.name) {
       if (synthetic_trial_groups_[i].id.group != trial.id.group) {
         synthetic_trial_groups_[i].id.group = trial.id.group;
         synthetic_trial_groups_[i].start_time = base::TimeTicks::Now();
+        NotifySyntheticTrialObservers();
       }
       return;
     }
   }
 
   SyntheticTrialGroup trial_group = trial;
   trial_group.start_time = base::TimeTicks::Now();
   synthetic_trial_groups_.push_back(trial_group);
+  NotifySyntheticTrialObservers();
 }
 
 void MetricsService::RegisterMetricsProvider(
     scoped_ptr<MetricsProvider> provider) {
   DCHECK_EQ(INITIALIZED, state_);
   metrics_providers_.push_back(provider.release());
 }
 
 void MetricsService::CheckForClonedInstall(
     scoped_refptr<base::SingleThreadTaskRunner> task_runner) {
   state_manager_->CheckForClonedInstall(task_runner);
 }
 
+void MetricsService::NotifySyntheticTrialObservers() {
+  FOR_EACH_OBSERVER(SyntheticTrialObserver, synthetic_trial_observer_list_,
+                    OnSyntheticTrialsChanged(synthetic_trial_groups_));
+}
+
 void MetricsService::GetCurrentSyntheticFieldTrials(
     std::vector<variations::ActiveGroupId>* synthetic_trials) {
   DCHECK(synthetic_trials);
   synthetic_trials->clear();
   const MetricsLog* current_log = log_manager_.current_log();
   for (size_t i = 0; i < synthetic_trial_groups_.size(); ++i) {
     if (synthetic_trial_groups_[i].start_time <= current_log->creation_time())
       synthetic_trials->push_back(synthetic_trial_groups_[i].id);
   }
 }
@@ skipping 53 matching lines @@
   local_state_->SetBoolean(path, value);
   RecordCurrentState(local_state_);
 }
 
 void MetricsService::RecordCurrentState(PrefService* pref) {
   pref->SetInt64(prefs::kStabilityLastTimestampSec,
                  base::Time::Now().ToTimeT());
 }
 
 }  // namespace metrics