Make VariationsService simulate received seeds.

chrome/browser/metrics/variations/variations_service.cc

Index: chrome/browser/metrics/variations/variations_service.cc
===================================================================
--- chrome/browser/metrics/variations/variations_service.cc	(revision 265923)
+++ chrome/browser/metrics/variations/variations_service.cc	(working copy)
@@ -12,6 +12,7 @@
 #include "base/metrics/sparse_histogram.h"
 #include "base/prefs/pref_registry_simple.h"
 #include "base/prefs/pref_service.h"
+#include "base/timer/elapsed_timer.h"
 #include "base/version.h"
 #include "chrome/browser/browser_process.h"
 #include "chrome/browser/network_time/network_time_tracker.h"
@@ -20,6 +21,7 @@
 #include "components/user_prefs/pref_registry_syncable.h"
 #include "components/variations/proto/variations_seed.pb.h"
 #include "components/variations/variations_seed_processor.h"
+#include "components/variations/variations_seed_simulator.h"
 #include "content/public/browser/browser_thread.h"
 #include "net/base/load_flags.h"
 #include "net/base/net_errors.h"
@@ -381,9 +383,46 @@
 void VariationsService::StoreSeed(const std::string& seed_data,
                                   const std::string& seed_signature,
                                   const base::Time& date_fetched) {
-  if (!seed_store_.StoreSeedData(seed_data, seed_signature, date_fetched))
+  VariationsSeed seed;
+  if (!seed_store_.StoreSeedData(seed_data, seed_signature, date_fetched,
+                                 &seed)) {
     return;
+  }
   RecordLastFetchTime();
+
+  const base::ElapsedTimer timer;
+
+  // TODO(asvitkine): Get the version that will be used on restart instead of
+  // the current version (i.e. if an update has been downloaded).
+  const chrome::VersionInfo current_version_info;
+  if (!current_version_info.is_valid())
+    return;
+
+  const base::Version current_version(current_version_info.Version());
+  if (!current_version.IsValid())
+    return;
+
+  const base::FieldTrial::EntropyProvider* entropy_provider =
+      base::FieldTrialList::GetEntropyProviderForOneTimeRandomization();
+  // One-time randomization should be supported by the global FieldTrialList in
+  // the process the VariationService is running in, so |entropy_provider| must
+  // be non-NULL.
+  DCHECK(entropy_provider);
+  VariationsSeedSimulator seed_simulator(*entropy_provider);
+
+  VariationsSeedSimulator::Result result = seed_simulator.SimulateSeedStudies(
+      seed, g_browser_process->GetApplicationLocale(),
+      GetReferenceDateForExpiryChecks(local_state_), current_version,
+      GetChannelForVariations(), GetCurrentFormFactor());
+
+  UMA_HISTOGRAM_COUNTS_100("Variations.SimulateSeed.NormalChanges",
+                           result.normal_group_change_count);
+  UMA_HISTOGRAM_COUNTS_100("Variations.SimulateSeed.KillBestEffortChanges",
+                           result.kill_best_effort_group_change_count);
+  UMA_HISTOGRAM_COUNTS_100("Variations.SimulateSeed.KillCriticalChanges",
+                           result.kill_critical_group_change_count);
+
+  UMA_HISTOGRAM_TIMES("Variations.SimulateSeed.Duration", timer.Elapsed());
 }
 
 void VariationsService::FetchVariationsSeed() {