Use low entropy for studies that send experiment IDs to Google properties.

components/variations/variations_seed_processor.cc

Index: components/variations/variations_seed_processor.cc
diff --git a/components/variations/variations_seed_processor.cc b/components/variations/variations_seed_processor.cc
index e169e7541019845df4e4438bc90be1692b8cd0b2..ff7b6cccc2ce4881b2725d2a0bd68cf1c727bf11 100644
--- a/components/variations/variations_seed_processor.cc
+++ b/components/variations/variations_seed_processor.cc
@@ -168,6 +168,19 @@ bool ShouldForceExperiment(const Study_Experiment& experiment,
   return false;
 }
 
+bool ShouldStudyUseLowEntropy(const Study& study) {
+  for (int i = 0; i < study.experiment_size(); ++i) {
+    const Study_Experiment& experiment = study.experiment(i);
+    if (experiment.has_google_web_experiment_id() ||
+        experiment.has_google_web_trigger_experiment_id() ||
+        experiment.has_google_update_experiment_id() ||
+        experiment.has_chrome_sync_experiment_id()) {
+      return true;
+    }
+  }
+  return false;
+}
+
 }  // namespace
 
 VariationsSeedProcessor::VariationsSeedProcessor() {
@@ -187,7 +200,8 @@ void VariationsSeedProcessor::CreateTrialsFromSeed(
     const std::string& session_consistency_country,
     const std::string& permanent_consistency_country,
     const UIStringOverrideCallback& override_callback,
-    base::FeatureList* feature_list) {
+    base::FeatureList* feature_list,
+    const base::FieldTrial::EntropyProvider* low_entropy_provider) {
   std::vector<ProcessedStudy> filtered_studies;
   FilterAndValidateStudies(seed, locale, reference_date, version, channel,
                            form_factor, hardware_class,
@@ -195,13 +209,15 @@ void VariationsSeedProcessor::CreateTrialsFromSeed(
                            permanent_consistency_country, &filtered_studies);
 
   for (size_t i = 0; i < filtered_studies.size(); ++i)
-    CreateTrialFromStudy(filtered_studies[i], override_callback, feature_list);
+    CreateTrialFromStudy(filtered_studies[i], override_callback, feature_list,
+                         low_entropy_provider);
 }
 
 void VariationsSeedProcessor::CreateTrialFromStudy(
     const ProcessedStudy& processed_study,
     const UIStringOverrideCallback& override_callback,
-    base::FeatureList* feature_list) {
+    base::FeatureList* feature_list,
+    const base::FieldTrial::EntropyProvider* low_entropy_provider) {
   const Study& study = *processed_study.study();
 
   // Check if any experiments need to be forced due to a command line
@@ -255,7 +271,8 @@ void VariationsSeedProcessor::CreateTrialFromStudy(
           study.name(), processed_study.total_probability(),
           study.default_experiment_name(),
           base::FieldTrialList::kNoExpirationYear, 1, 1, randomization_type,
-          randomization_seed, NULL));
+          randomization_seed, NULL,
+          ShouldStudyUseLowEntropy(study) ? low_entropy_provider : NULL));
 
   bool has_overrides = false;
   bool enables_or_disables_features = false;