Expand FeatureList to support FieldTrial association.

components/variations/service/variations_service.h

Index: components/variations/service/variations_service.h
diff --git a/components/variations/service/variations_service.h b/components/variations/service/variations_service.h
index def6124eed20fa139976b82dac3c103f56523809..32fd34b4bae9bb396e480ddf5136e87b04b631af 100644
--- a/components/variations/service/variations_service.h
+++ b/components/variations/service/variations_service.h
@@ -28,6 +28,7 @@ class PrefService;
 class PrefRegistrySimple;
 
 namespace base {
+class FeatureList;
 class Version;
 }
 
@@ -72,10 +73,12 @@ class VariationsService
 
   ~VariationsService() override;
 
-  // Creates field trials based on Variations Seed loaded from local prefs. If
-  // there is a problem loading the seed data, all trials specified by the seed
-  // may not be created.
-  bool CreateTrialsFromSeed();
+  // Creates field trials based on the variations seed loaded from local state.
+  // If there is a problem loading the seed data, all trials specified by the
+  // seed may not be created. Some field trials are configured to override or
+  // associate with (for reporting) specific features. These associations are
+  // registered with |feature_list|.
+  bool CreateTrialsFromSeed(base::FeatureList* feature_list);
 
   // Should be called before startup of the main message loop.
   void PerformPreMainMessageLoopStartup();