Pref service: add support for tracked prefs.

services/preferences/tracked/segregated_pref_store.h

Index: services/preferences/tracked/segregated_pref_store.h
diff --git a/services/preferences/tracked/segregated_pref_store.h b/services/preferences/tracked/segregated_pref_store.h
index 8118dd5fc1aec28715a0b507515a6dc14d270ab4..3621e49aa079cb09c49549eeac5de8b9688f3867 100644
--- a/services/preferences/tracked/segregated_pref_store.h
+++ b/services/preferences/tracked/segregated_pref_store.h
@@ -16,6 +16,7 @@
 #include "base/memory/ref_counted.h"
 #include "base/observer_list.h"
 #include "components/prefs/persistent_pref_store.h"
+#include "services/preferences/public/interfaces/tracked_preference_validation_delegate.mojom.h"
 
 // Provides a unified PersistentPrefStore implementation that splits its storage
 // and retrieval between two underlying PersistentPrefStore instances: a set of
@@ -43,7 +44,8 @@ class SegregatedPrefStore : public PersistentPrefStore {
   SegregatedPrefStore(
       const scoped_refptr<PersistentPrefStore>& default_pref_store,
       const scoped_refptr<PersistentPrefStore>& selected_pref_store,
-      const std::set<std::string>& selected_pref_names);
+      const std::set<std::string>& selected_pref_names,
+      prefs::mojom::TrackedPreferenceValidationDelegatePtr validation_delegate);
 
   // PrefStore implementation
   void AddObserver(Observer* observer) override;
@@ -101,6 +103,11 @@ class SegregatedPrefStore : public PersistentPrefStore {
   PersistentPrefStore* StoreForKey(const std::string& key);
   const PersistentPrefStore* StoreForKey(const std::string& key) const;
 
+  // |validation_delegate_| is used by |default_pref_store_| and
+  // |selected_pref_store_| PrefHashFilters. Its lifetime is managed here since
+  // a single owner is required.
+  prefs::mojom::TrackedPreferenceValidationDelegatePtr validation_delegate_;
+
   scoped_refptr<PersistentPrefStore> default_pref_store_;
   scoped_refptr<PersistentPrefStore> selected_pref_store_;
   std::set<std::string> selected_preference_names_;