Revert of Pref service: add support for tracked prefs.

services/preferences/tracked/segregated_pref_store.cc

Index: services/preferences/tracked/segregated_pref_store.cc
diff --git a/services/preferences/tracked/segregated_pref_store.cc b/services/preferences/tracked/segregated_pref_store.cc
index af7349e0382f6a9ba07df994d017d85ac762eef8..8ddc5c040d1555c5e6a190c837026a92c2d22d25 100644
--- a/services/preferences/tracked/segregated_pref_store.cc
+++ b/services/preferences/tracked/segregated_pref_store.cc
@@ -51,10 +51,8 @@
 SegregatedPrefStore::SegregatedPrefStore(
     const scoped_refptr<PersistentPrefStore>& default_pref_store,
     const scoped_refptr<PersistentPrefStore>& selected_pref_store,
-    const std::set<std::string>& selected_pref_names,
-    prefs::mojom::TrackedPreferenceValidationDelegatePtr validation_delegate)
-    : validation_delegate_(std::move(validation_delegate)),
-      default_pref_store_(default_pref_store),
+    const std::set<std::string>& selected_pref_names)
+    : default_pref_store_(default_pref_store),
       selected_pref_store_(selected_pref_store),
       selected_preference_names_(selected_pref_names),
       aggregating_observer_(this) {