Pref service: add support for tracked prefs.

services/preferences/public/interfaces/preferences_configuration.mojom

Index: services/preferences/public/interfaces/preferences_configuration.mojom
diff --git a/services/preferences/public/interfaces/preferences_configuration.mojom b/services/preferences/public/interfaces/preferences_configuration.mojom
index d2bd39a88011699517100e74c1b13b3ff20994df..76f7785ae06a260085906affae6da2a8f2462a5b 100644
--- a/services/preferences/public/interfaces/preferences_configuration.mojom
+++ b/services/preferences/public/interfaces/preferences_configuration.mojom
@@ -5,15 +5,33 @@
 module prefs.mojom;
 
 import "mojo/common/file_path.mojom";
+import "mojo/common/string16.mojom";
+import "services/preferences/public/interfaces/tracked_preference_validation_delegate.mojom";
 
 union PersistentPrefStoreConfiguration {
   SimplePersistentPrefStoreConfiguration simple_configuration;
+  TrackedPersistentPrefStoreConfiguration tracked_configuration;
 };
 
 struct SimplePersistentPrefStoreConfiguration {
   mojo.common.mojom.FilePath pref_filename;
 };
 
+// These parameters are passed to prefs::CreateTrackedPersistentPrefStore() in
+// services/preferences/persistent_pref_store_factory.cc.
+struct TrackedPersistentPrefStoreConfiguration {
+  mojo.common.mojom.FilePath unprotected_pref_filename;
+  mojo.common.mojom.FilePath protected_pref_filename;
+  array<TrackedPreferenceMetadata> tracking_configuration;
+  uint64 reporting_ids_count;
+  string seed;
+  string legacy_device_id;
+  string registry_seed;
+  mojo.common.mojom.String16 registry_path;
+  TrackedPreferenceValidationDelegate? validation_delegate;
+  ResetOnLoadObserver? reset_on_load_observer;
+};
+
 struct TrackedPreferenceMetadata {
   enum EnforcementLevel { NO_ENFORCEMENT, ENFORCE_ON_LOAD };
 
@@ -38,3 +56,7 @@ struct TrackedPreferenceMetadata {
   PrefTrackingStrategy strategy;
   ValueType value_type;
 };
+
+interface ResetOnLoadObserver {
+  OnResetOnLoad();
+};