Add other variations (with ids) for NTPSnippets to chrome://flags

components/flags_ui/feature_entry.h

Index: components/flags_ui/feature_entry.h
diff --git a/components/flags_ui/feature_entry.h b/components/flags_ui/feature_entry.h
index 5c44bc3334f3e16e236faae040cc7042e42aa565..ec192d9212776333093edf138f563e7aa7056112 100644
--- a/components/flags_ui/feature_entry.h
+++ b/components/flags_ui/feature_entry.h
@@ -99,6 +99,10 @@ struct FeatureEntry {
     const char* description_text;
     const FeatureParam* params;
     int num_params;
+    // A variation id number in the format of
+    // VariationsHttpHeaderProvider::SetDefaultVariationIds or an empty string
+    // if you do not need to set any variation_id for this feature variation.
+    std::string variation_id;
   };
 
   // The internal name of the feature entry. This is never shown to the user.