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

components/variations/variations_seed_simulator.h

Index: components/variations/variations_seed_simulator.h
diff --git a/components/variations/variations_seed_simulator.h b/components/variations/variations_seed_simulator.h
index dafaf098afe5f9bde01222f3826232a41070abc3..c18e6c3210a10a31db24d10143e2fc60e685b60c 100644
--- a/components/variations/variations_seed_simulator.h
+++ b/components/variations/variations_seed_simulator.h
@@ -44,9 +44,14 @@ class VariationsSeedSimulator {
     ~Result();
   };
 
-  // Creates the simulator with the given entropy |provider|.
-  explicit VariationsSeedSimulator(
-      const base::FieldTrial::EntropyProvider& provider);
+  // Creates the simulator with the given default and low entropy providers. The
+  // |low_entropy_provider| will be used for studies that should only use a low
+  // entropy source. This is defined by
+  // VariationsSeedProcessor::ShouldStudyUseLowEntropy, in
+  // variations_seed_processor.h.
+  VariationsSeedSimulator(
+      const base::FieldTrial::EntropyProvider& default_entropy_provider,
+      const base::FieldTrial::EntropyProvider& low_entropy_provider);
   virtual ~VariationsSeedSimulator();
 
   // Computes differences between the current process' field trial state and
@@ -97,7 +102,8 @@ class VariationsSeedSimulator {
   ChangeType SessionStudyGroupChanged(const ProcessedStudy& filtered_study,
                                       const std::string& selected_group);
 
-  const base::FieldTrial::EntropyProvider& entropy_provider_;
+  const base::FieldTrial::EntropyProvider& default_entropy_provider_;
+  const base::FieldTrial::EntropyProvider& low_entropy_provider_;
 
   DISALLOW_COPY_AND_ASSIGN(VariationsSeedSimulator);
 };